21591005769 has 6 divisors (see below), whose sum is σ = 31187008346. Its totient is φ = 14394003840.

The previous prime is 21591005753. The next prime is 21591005773. The reversal of 21591005769 is 96750019512.

21591005769 is a `hidden beast` number, since 2 + 1 + 591 + 0 + 0 + 57 + 6 + 9 = 666.

It can be written as a sum of positive squares in only one way, i.e., 12108141369 + 9482864400 = 110037^2 + 97380^2 .

It is not a de Polignac number, because 21591005769 - 2⁴ = 21591005753 is a prime.

It is a super-2 number, since 2×21591005769² (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 (21591005369) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1199500312 + ... + 1199500329.

Almost surely, 2^21591005769 is an apocalyptic number.

It is an amenable number.

21591005769 is a deficient number, since it is larger than the sum of its proper divisors (9596002577).

21591005769 is a wasteful number, since it uses less digits than its factorization.

21591005769 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2399000647 (or 2399000644 counting only the distinct ones).

The product of its (nonzero) digits is 170100, while the sum is 45.

The spelling of 21591005769 in words is "twenty-one billion, five hundred ninety-one million, five thousand, seven hundred sixty-nine".