20391967 has 2 divisors, whose sum is σ = 20391968. Its totient is φ = 20391966.

The previous prime is 20391929. The next prime is 20391979. The reversal of 20391967 is 76919302.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20391967 - 2²³ = 12003359 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20391907) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10195983 + 10195984.

It is an arithmetic number, because the mean of its divisors is an integer number (10195984).

Almost surely, 2^20391967 is an apocalyptic number.

20391967 is a deficient number, since it is larger than the sum of its proper divisors (1).

20391967 is an equidigital number, since it uses as much as digits as its factorization.

20391967 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20412, while the sum is 37.

The square root of 20391967 is about 4515.7465606475. The cubic root of 20391967 is about 273.2035719918.

The spelling of 20391967 in words is "twenty million, three hundred ninety-one thousand, nine hundred sixty-seven".