20981990400 has 528 divisors, whose sum is σ = 81874759680. Its totient is φ = 4637491200.

The previous prime is 20981990399. The next prime is 20981990473. The reversal of 20981990400 is 409918902.

It is a super-2 number, since 2×20981990400² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 16664971 + ... + 16666229.

Almost surely, 2^20981990400 is an apocalyptic number.

20981990400 is a gapful number since it is divisible by the number (20) 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 20981990400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40937379840).

20981990400 is an abundant number, since it is smaller than the sum of its proper divisors (60892769280).

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

20981990400 is a wasteful number, since it uses less digits than its factorization.

20981990400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1330 (or 1307 counting only the distinct ones).

The product of its (nonzero) digits is 46656, while the sum is 42.

The spelling of 20981990400 in words is "twenty billion, nine hundred eighty-one million, nine hundred ninety thousand, four hundred".