21665162451 has 16 divisors (see below), whose sum is σ = 29053446048. Its totient is φ = 14360371200.

The previous prime is 21665162429. The next prime is 21665162473. The reversal of 21665162451 is 15426156612.

It is an interprime number because it is at equal distance from previous prime (21665162429) and next prime (21665162473).

It is not a de Polignac number, because 21665162451 - 2¹¹ = 21665160403 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21665162401) 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, 391141 + ... + 443081.

It is an arithmetic number, because the mean of its divisors is an integer number (1815840378).

Almost surely, 2^21665162451 is an apocalyptic number.

21665162451 is a deficient number, since it is larger than the sum of its proper divisors (7388283597).

21665162451 is a wasteful number, since it uses less digits than its factorization.

21665162451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52742.

The product of its digits is 86400, while the sum is 39.

The spelling of 21665162451 in words is "twenty-one billion, six hundred sixty-five million, one hundred sixty-two thousand, four hundred fifty-one".