21697051008 has 192 divisors, whose sum is σ = 59845338000. Its totient is φ = 6964420608.

The previous prime is 21697050979. The next prime is 21697051009. The reversal of 21697051008 is 80015079612.

It is a tau number, because it is divible by the number of its divisors (192).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21697051009) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 78328566 + ... + 78328842.

Almost surely, 2^21697051008 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21697051008, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29922669000).

21697051008 is an abundant number, since it is smaller than the sum of its proper divisors (38148286992).

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

21697051008 is a wasteful number, since it uses less digits than its factorization.

21697051008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 517 (or 468 counting only the distinct ones).

The product of its (nonzero) digits is 30240, while the sum is 39.

The spelling of 21697051008 in words is "twenty-one billion, six hundred ninety-seven million, fifty-one thousand, eight".