21057723031 has 2 divisors, whose sum is σ = 21057723032. Its totient is φ = 21057723030.

The previous prime is 21057722999. The next prime is 21057723083. The reversal of 21057723031 is 13032775012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21057723031 - 2⁵ = 21057722999 is a prime.

It is a super-2 number, since 2×21057723031² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21057722984 and 21057723002.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21057723131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10528861515 + 10528861516.

It is an arithmetic number, because the mean of its divisors is an integer number (10528861516).

Almost surely, 2^21057723031 is an apocalyptic number.

21057723031 is a deficient number, since it is larger than the sum of its proper divisors (1).

21057723031 is an equidigital number, since it uses as much as digits as its factorization.

21057723031 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8820, while the sum is 31.

The spelling of 21057723031 in words is "twenty-one billion, fifty-seven million, seven hundred twenty-three thousand, thirty-one".