20928431 has 2 divisors, whose sum is σ = 20928432. Its totient is φ = 20928430.

The previous prime is 20928419. The next prime is 20928437. The reversal of 20928431 is 13482902.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20928431 - 2¹⁸ = 20666287 is a prime.

It is a super-2 number, since 2×20928431² = 875998448243522, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 20928394 and 20928403.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20928437) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10464215 + 10464216.

It is an arithmetic number, because the mean of its divisors is an integer number (10464216).

Almost surely, 2^20928431 is an apocalyptic number.

20928431 is a deficient number, since it is larger than the sum of its proper divisors (1).

20928431 is an equidigital number, since it uses as much as digits as its factorization.

20928431 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3456, while the sum is 29.

The square root of 20928431 is about 4574.7602122953. The cubic root of 20928431 is about 275.5786427488.

The spelling of 20928431 in words is "twenty million, nine hundred twenty-eight thousand, four hundred thirty-one".