21072507731 has 16 divisors (see below), whose sum is σ = 23226588000. Its totient is φ = 18958579200.

The previous prime is 21072507689. The next prime is 21072507733. The reversal of 21072507731 is 13770527012.

It is not a de Polignac number, because 21072507731 - 2⁶ = 21072507667 is a prime.

It is a super-2 number, since 2×21072507731² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21072507691 and 21072507700.

It is not an unprimeable number, because it can be changed into a prime (21072507733) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1046345 + ... + 1066293.

It is an arithmetic number, because the mean of its divisors is an integer number (1451661750).

Almost surely, 2^21072507731 is an apocalyptic number.

21072507731 is a deficient number, since it is larger than the sum of its proper divisors (2154080269).

21072507731 is a wasteful number, since it uses less digits than its factorization.

21072507731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20950.

The product of its (nonzero) digits is 20580, while the sum is 35.

The spelling of 21072507731 in words is "twenty-one billion, seventy-two million, five hundred seven thousand, seven hundred thirty-one".