21506644365 has 8 divisors (see below), whose sum is σ = 34410631008. Its totient is φ = 11470210320.

The previous prime is 21506644343. The next prime is 21506644409. The reversal of 21506644365 is 56344660512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21506644365 - 2⁶ = 21506644301 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 716888131 + ... + 716888160.

It is an arithmetic number, because the mean of its divisors is an integer number (4301328876).

Almost surely, 2^21506644365 is an apocalyptic number.

It is an amenable number.

21506644365 is a deficient number, since it is larger than the sum of its proper divisors (12903986643).

21506644365 is a wasteful number, since it uses less digits than its factorization.

21506644365 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1433776299.

The product of its (nonzero) digits is 518400, while the sum is 42.

The spelling of 21506644365 in words is "twenty-one billion, five hundred six million, six hundred forty-four thousand, three hundred sixty-five".