21065631819 has 16 divisors (see below), whose sum is σ = 28439534592. Its totient is φ = 13867904288.

The previous prime is 21065631817. The next prime is 21065631863. The reversal of 21065631819 is 91813656012.

It is a cyclic number.

It is not a de Polignac number, because 21065631819 - 2¹ = 21065631817 is a prime.

It is a super-2 number, since 2×21065631819² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21065631817) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 530377 + ... + 568709.

It is an arithmetic number, because the mean of its divisors is an integer number (1777470912).

Almost surely, 2^21065631819 is an apocalyptic number.

21065631819 is a deficient number, since it is larger than the sum of its proper divisors (7373902773).

21065631819 is a wasteful number, since it uses less digits than its factorization.

21065631819 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40626.

The product of its (nonzero) digits is 77760, while the sum is 42.

The spelling of 21065631819 in words is "twenty-one billion, sixty-five million, six hundred thirty-one thousand, eight hundred nineteen".