642931631 has 4 divisors (see below), whose sum is σ = 644364000. Its totient is φ = 641499264.

The previous prime is 642931621. The next prime is 642931669. The reversal of 642931631 is 136139246.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 136139246 = 2 ⋅68069623.

It is a cyclic number.

It is not a de Polignac number, because 642931631 - 2⁶ = 642931567 is a prime.

It is a super-2 number, since 2×642931631² = 826722164280640322, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 642931591 and 642931600.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642931621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 715511 + ... + 716408.

It is an arithmetic number, because the mean of its divisors is an integer number (161091000).

Almost surely, 2^642931631 is an apocalyptic number.

642931631 is a deficient number, since it is larger than the sum of its proper divisors (1432369).

642931631 is a wasteful number, since it uses less digits than its factorization.

642931631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1432368.

The product of its digits is 23328, while the sum is 35.

The square root of 642931631 is about 25356.0965252935. The cubic root of 642931631 is about 863.0877068744.

The spelling of 642931631 in words is "six hundred forty-two million, nine hundred thirty-one thousand, six hundred thirty-one".