21691786480 has 480 divisors, whose sum is σ = 68010897024. Its totient is φ = 6372753408.

The previous prime is 21691786453. The next prime is 21691786511. The reversal of 21691786480 is 8468719612.

It is a Harshad number since it is a multiple of its sum of digits (52).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 297147724 + ... + 297147796.

Almost surely, 2^21691786480 is an apocalyptic number.

21691786480 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 21691786480, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34005448512).

21691786480 is an abundant number, since it is smaller than the sum of its proper divisors (46319110544).

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

21691786480 is an equidigital number, since it uses as much as digits as its factorization.

21691786480 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 151 (or 117 counting only the distinct ones).

The product of its (nonzero) digits is 1161216, while the sum is 52.

The spelling of 21691786480 in words is "twenty-one billion, six hundred ninety-one million, seven hundred eighty-six thousand, four hundred eighty".