20998937987456 has 128 divisors (see below), whose sum is σ = 49175634332160. Its totient is φ = 8805686446080.

The previous prime is 20998937987453. The next prime is 20998937987459. The reversal of 20998937987456 is 65478973989902.

It is an interprime number because it is at equal distance from previous prime (20998937987453) and next prime (20998937987459).

It is a tau number, because it is divible by the number of its divisors (128).

It is a super-2 number, since 2×20998937987456² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20998937987453) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 31648745 + ... + 32305431.

It is an arithmetic number, because the mean of its divisors is an integer number (384184643220).

Almost surely, 2^{20998937987456} is an apocalyptic number.

20998937987456 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20998937987456, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24587817166080).

20998937987456 is an abundant number, since it is smaller than the sum of its proper divisors (28176696344704).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20998937987456 is a wasteful number, since it uses less digits than its factorization.

20998937987456 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 658472 (or 658460 counting only the distinct ones).

The product of its (nonzero) digits is 14814213120, while the sum is 86.

The spelling of 20998937987456 in words is "twenty trillion, nine hundred ninety-eight billion, nine hundred thirty-seven million, nine hundred eighty-seven thousand, four hundred fifty-six".