21651767411761 has 16 divisors (see below), whose sum is σ = 21906094855680. Its totient is φ = 21399299066880.

The previous prime is 21651767411753. The next prime is 21651767411779. The reversal of 21651767411761 is 16711476715612.

It is a cyclic number.

It is not a de Polignac number, because 21651767411761 - 2³ = 21651767411753 is a prime.

It is a super-2 number, since 2×21651767411761² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21651767411161) 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, 20619855 + ... + 21644443.

It is an arithmetic number, because the mean of its divisors is an integer number (1369130928480).

Almost surely, 2^{21651767411761} is an apocalyptic number.

It is an amenable number.

21651767411761 is a deficient number, since it is larger than the sum of its proper divisors (254327443919).

21651767411761 is a wasteful number, since it uses less digits than its factorization.

21651767411761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1025496.

The product of its digits is 2963520, while the sum is 55.

The spelling of 21651767411761 in words is "twenty-one trillion, six hundred fifty-one billion, seven hundred sixty-seven million, four hundred eleven thousand, seven hundred sixty-one".