21727272665 has 16 divisors (see below), whose sum is σ = 29820438912. Its totient is φ = 14887183104.

The previous prime is 21727272629. The next prime is 21727272683. The reversal of 21727272665 is 56627272712.

It is a cyclic number.

It is not a de Polignac number, because 21727272665 - 2¹⁴ = 21727256281 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 193919 + ... + 284708.

It is an arithmetic number, because the mean of its divisors is an integer number (1863777432).

Almost surely, 2^21727272665 is an apocalyptic number.

It is an amenable number.

21727272665 is a deficient number, since it is larger than the sum of its proper divisors (8093166247).

21727272665 is a wasteful number, since it uses less digits than its factorization.

21727272665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 479936.

The product of its digits is 987840, while the sum is 47.

Adding to 21727272665 its sum of digits (47), we get a palindrome (21727272712).

The spelling of 21727272665 in words is "twenty-one billion, seven hundred twenty-seven million, two hundred seventy-two thousand, six hundred sixty-five".