21731131761 has 4 divisors (see below), whose sum is σ = 28974842352. Its totient is φ = 14487421172.

The previous prime is 21731131727. The next prime is 21731131771. The reversal of 21731131761 is 16713113712.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21731131761 - 2¹¹ = 21731129713 is a prime.

It is a super-2 number, since 2×21731131761² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21731131771) 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, 3621855291 + ... + 3621855296.

It is an arithmetic number, because the mean of its divisors is an integer number (7243710588).

Almost surely, 2^21731131761 is an apocalyptic number.

It is an amenable number.

21731131761 is a deficient number, since it is larger than the sum of its proper divisors (7243710591).

21731131761 is an equidigital number, since it uses as much as digits as its factorization.

21731131761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7243710590.

The product of its digits is 5292, while the sum is 33.

The spelling of 21731131761 in words is "twenty-one billion, seven hundred thirty-one million, one hundred thirty-one thousand, seven hundred sixty-one".