20565731 has 2 divisors, whose sum is σ = 20565732. Its totient is φ = 20565730.

The previous prime is 20565719. The next prime is 20565737. The reversal of 20565731 is 13756502.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20565731 - 2⁶ = 20565667 is a prime.

It is a super-2 number, since 2×20565731² = 845898583128722, which contains 22 as substring.

It is a Sophie Germain prime.

It is a junction number, because it is equal to n+sod(n) for n = 20565694 and 20565703.

It is not a weakly prime, because it can be changed into another prime (20565737) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10282865 + 10282866.

It is an arithmetic number, because the mean of its divisors is an integer number (10282866).

Almost surely, 2^20565731 is an apocalyptic number.

20565731 is a deficient number, since it is larger than the sum of its proper divisors (1).

20565731 is an equidigital number, since it uses as much as digits as its factorization.

20565731 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6300, while the sum is 29.

The square root of 20565731 is about 4534.9455344028. The cubic root of 20565731 is about 273.9773854922.

The spelling of 20565731 in words is "twenty million, five hundred sixty-five thousand, seven hundred thirty-one".