642931 has 2 divisors, whose sum is σ = 642932. Its totient is φ = 642930.

The previous prime is 642907. The next prime is 642937. The reversal of 642931 is 139246.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 642931 - 2⁵ = 642899 is a prime.

It is a super-2 number, since 2×642931² = 826720541522, which contains 22 as substring.

It is a nialpdrome in base 15.

It is a junction number, because it is equal to n+sod(n) for n = 642896 and 642905.

It is not a weakly prime, because it can be changed into another prime (642937) 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, 321465 + 321466.

It is an arithmetic number, because the mean of its divisors is an integer number (321466).

2⁶⁴²⁹³¹ is an apocalyptic number.

642931 is a deficient number, since it is larger than the sum of its proper divisors (1).

642931 is an equidigital number, since it uses as much as digits as its factorization.

642931 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1296, while the sum is 25.

The square root of 642931 is about 801.8297824352. The cubic root of 642931 is about 86.3087424518.

The spelling of 642931 in words is "six hundred forty-two thousand, nine hundred thirty-one".