642631787 has 4 divisors (see below), whose sum is σ = 734436336. Its totient is φ = 550827240.

The previous prime is 642631783. The next prime is 642631817. The reversal of 642631787 is 787136246.

642631787 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 642631787 - 2² = 642631783 is a prime.

It is a super-2 number, since 2×642631787² = 825951227325626738, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (642631783) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 45902264 + ... + 45902277.

It is an arithmetic number, because the mean of its divisors is an integer number (183609084).

Almost surely, 2^642631787 is an apocalyptic number.

642631787 is a deficient number, since it is larger than the sum of its proper divisors (91804549).

642631787 is an equidigital number, since it uses as much as digits as its factorization.

642631787 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91804548.

The product of its digits is 338688, while the sum is 44.

The square root of 642631787 is about 25350.1831748806. The cubic root of 642631787 is about 862.9535132841.

The spelling of 642631787 in words is "six hundred forty-two million, six hundred thirty-one thousand, seven hundred eighty-seven".