21175719731 has 2 divisors, whose sum is σ = 21175719732. Its totient is φ = 21175719730.

The previous prime is 21175719727. The next prime is 21175719749. The reversal of 21175719731 is 13791757112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21175719731 - 2² = 21175719727 is a prime.

It is a super-2 number, since 2×21175719731² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21175719781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10587859865 + 10587859866.

It is an arithmetic number, because the mean of its divisors is an integer number (10587859866).

Almost surely, 2^21175719731 is an apocalyptic number.

21175719731 is a deficient number, since it is larger than the sum of its proper divisors (1).

21175719731 is an equidigital number, since it uses as much as digits as its factorization.

21175719731 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 92610, while the sum is 44.

The spelling of 21175719731 in words is "twenty-one billion, one hundred seventy-five million, seven hundred nineteen thousand, seven hundred thirty-one".