21997157670 has 24 divisors (see below), whose sum is σ = 57192610176. Its totient is φ = 5865908688.

The previous prime is 21997157647. The next prime is 21997157731. The reversal of 21997157670 is 7675179912.

It is a happy number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 122206342 + ... + 122206521.

It is an arithmetic number, because the mean of its divisors is an integer number (2383025424).

Almost surely, 2^21997157670 is an apocalyptic number.

21997157670 is an abundant number, since it is smaller than the sum of its proper divisors (35195452506).

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

21997157670 is a wasteful number, since it uses less digits than its factorization.

21997157670 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 244412876 (or 244412873 counting only the distinct ones).

The product of its (nonzero) digits is 1666980, while the sum is 54.

The spelling of 21997157670 in words is "twenty-one billion, nine hundred ninety-seven million, one hundred fifty-seven thousand, six hundred seventy".