21697865280 has 560 divisors, whose sum is σ = 95004940800. Its totient is φ = 4577513472.

The previous prime is 21697865269. The next prime is 21697865303. The reversal of 21697865280 is 8256879612.

21697865280 is a `hidden beast` number, since 21 + 6 + 97 + 8 + 6 + 528 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (560).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 2354121 + ... + 2363319.

It is an arithmetic number, because the mean of its divisors is an integer number (169651680).

Almost surely, 2^21697865280 is an apocalyptic number.

21697865280 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 21697865280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (47502470400).

21697865280 is an abundant number, since it is smaller than the sum of its proper divisors (73307075520).

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

21697865280 is a wasteful number, since it uses less digits than its factorization.

21697865280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9248 (or 9229 counting only the distinct ones).

The product of its (nonzero) digits is 2903040, while the sum is 54.

The spelling of 21697865280 in words is "twenty-one billion, six hundred ninety-seven million, eight hundred sixty-five thousand, two hundred eighty".