21306142665 has 32 divisors (see below), whose sum is σ = 37885449600. Its totient is φ = 11360917440.

The previous prime is 21306142639. The next prime is 21306142679. The reversal of 21306142665 is 56624160312.

21306142665 is a `hidden beast` number, since 2 + 1 + 30 + 614 + 2 + 6 + 6 + 5 = 666.

It is not a de Polignac number, because 21306142665 - 2⁵ = 21306142633 is a prime.

It is a super-2 number, since 2×21306142665² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 778870 + ... + 805760.

It is an arithmetic number, because the mean of its divisors is an integer number (1183920300).

Almost surely, 2^21306142665 is an apocalyptic number.

It is an amenable number.

21306142665 is a deficient number, since it is larger than the sum of its proper divisors (16579306935).

21306142665 is a wasteful number, since it uses less digits than its factorization.

21306142665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32774 (or 32768 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 36.

The spelling of 21306142665 in words is "twenty-one billion, three hundred six million, one hundred forty-two thousand, six hundred sixty-five".