21727564231 has 4 divisors (see below), whose sum is σ = 22257504864. Its totient is φ = 21197623600.

The previous prime is 21727564211. The next prime is 21727564277. The reversal of 21727564231 is 13246572712.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21727564231 - 2²¹ = 21725467079 is a prime.

It is a super-2 number, since 2×21727564231² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21727564211) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 264970255 + ... + 264970336.

It is an arithmetic number, because the mean of its divisors is an integer number (5564376216).

Almost surely, 2^21727564231 is an apocalyptic number.

21727564231 is a deficient number, since it is larger than the sum of its proper divisors (529940633).

21727564231 is an equidigital number, since it uses as much as digits as its factorization.

21727564231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 529940632.

The product of its digits is 141120, while the sum is 40.

The spelling of 21727564231 in words is "twenty-one billion, seven hundred twenty-seven million, five hundred sixty-four thousand, two hundred thirty-one".