21939056637 has 4 divisors (see below), whose sum is σ = 29252075520. Its totient is φ = 14626037756.

The previous prime is 21939056611. The next prime is 21939056639. The reversal of 21939056637 is 73665093912.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21939056637 - 2⁷ = 21939056509 is a prime.

It is a super-2 number, since 2×21939056637² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21939056637.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21939056639) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3656509437 + ... + 3656509442.

It is an arithmetic number, because the mean of its divisors is an integer number (7313018880).

Almost surely, 2^21939056637 is an apocalyptic number.

It is an amenable number.

21939056637 is a deficient number, since it is larger than the sum of its proper divisors (7313018883).

21939056637 is an equidigital number, since it uses as much as digits as its factorization.

21939056637 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7313018882.

The product of its (nonzero) digits is 1837080, while the sum is 51.

The spelling of 21939056637 in words is "twenty-one billion, nine hundred thirty-nine million, fifty-six thousand, six hundred thirty-seven".