21056659737 has 4 divisors (see below), whose sum is σ = 28075546320. Its totient is φ = 14037773156.

The previous prime is 21056659721. The next prime is 21056659753. The reversal of 21056659737 is 73795665012.

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 an interprime number because it is at equal distance from previous prime (21056659721) and next prime (21056659753).

It is a cyclic number.

It is not a de Polignac number, because 21056659737 - 2⁴ = 21056659721 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21056659737.

It is not an unprimeable number, because it can be changed into a prime (21056659837) 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, 3509443287 + ... + 3509443292.

It is an arithmetic number, because the mean of its divisors is an integer number (7018886580).

Almost surely, 2^21056659737 is an apocalyptic number.

It is an amenable number.

21056659737 is a deficient number, since it is larger than the sum of its proper divisors (7018886583).

21056659737 is an equidigital number, since it uses as much as digits as its factorization.

21056659737 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7018886582.

The product of its (nonzero) digits is 2381400, while the sum is 51.

The spelling of 21056659737 in words is "twenty-one billion, fifty-six million, six hundred fifty-nine thousand, seven hundred thirty-seven".