21731504361 has 12 divisors (see below), whose sum is σ = 33706006992. Its totient is φ = 12418002408.

The previous prime is 21731504359. The next prime is 21731504369. The reversal of 21731504361 is 16340513712.

It is not a de Polignac number, because 21731504361 - 2¹ = 21731504359 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21731504369) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 73916535 + ... + 73916828.

It is an arithmetic number, because the mean of its divisors is an integer number (2808833916).

Almost surely, 2^21731504361 is an apocalyptic number.

21731504361 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21731504361 is a deficient number, since it is larger than the sum of its proper divisors (11974502631).

21731504361 is a wasteful number, since it uses less digits than its factorization.

21731504361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 147833380 (or 147833373 counting only the distinct ones).

The product of its (nonzero) digits is 15120, while the sum is 33.

The spelling of 21731504361 in words is "twenty-one billion, seven hundred thirty-one million, five hundred four thousand, three hundred sixty-one".