21557681769 has 32 divisors (see below), whose sum is σ = 31184199424. Its totient is φ = 13168189440.

The previous prime is 21557681729. The next prime is 21557681771. The reversal of 21557681769 is 96718675512.

It is not a de Polignac number, because 21557681769 - 2¹¹ = 21557679721 is a prime.

It is a super-2 number, since 2×21557681769² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21557681729) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3662709 + ... + 3668589.

It is an arithmetic number, because the mean of its divisors is an integer number (974506232).

Almost surely, 2^21557681769 is an apocalyptic number.

It is an amenable number.

21557681769 is a deficient number, since it is larger than the sum of its proper divisors (9626517655).

21557681769 is a wasteful number, since it uses less digits than its factorization.

21557681769 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6577.

The product of its digits is 6350400, while the sum is 57.

The spelling of 21557681769 in words is "twenty-one billion, five hundred fifty-seven million, six hundred eighty-one thousand, seven hundred sixty-nine".