21256928629 has 4 divisors (see below), whose sum is σ = 21297573376. Its totient is φ = 21216283884.

The previous prime is 21256928617. The next prime is 21256928789. The reversal of 21256928629 is 92682965212.

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 21256928629 - 2¹³ = 21256920437 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21256928029) 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, 20321589 + ... + 20322634.

It is an arithmetic number, because the mean of its divisors is an integer number (5324393344).

Almost surely, 2^21256928629 is an apocalyptic number.

It is an amenable number.

21256928629 is a deficient number, since it is larger than the sum of its proper divisors (40644747).

21256928629 is an equidigital number, since it uses as much as digits as its factorization.

21256928629 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40644746.

The product of its digits is 1866240, while the sum is 52.

The spelling of 21256928629 in words is "twenty-one billion, two hundred fifty-six million, nine hundred twenty-eight thousand, six hundred twenty-nine".