642815690 has 64 divisors (see below), whose sum is σ = 1313832960. Its totient is φ = 224328000.

The previous prime is 642815683. The next prime is 642815699. The reversal of 642815690 is 96518246.

It is a happy number.

It is a super-2 number, since 2×642815690² = 826424022620352200, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (642815699) 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 in 31 ways as a sum of consecutive naturals, for example, 445991 + ... + 447429.

It is an arithmetic number, because the mean of its divisors is an integer number (20528640).

Almost surely, 2^642815690 is an apocalyptic number.

642815690 is an abundant number, since it is smaller than the sum of its proper divisors (671017270).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

642815690 is a wasteful number, since it uses less digits than its factorization.

642815690 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1619.

The product of its (nonzero) digits is 103680, while the sum is 41.

The square root of 642815690 is about 25353.8101673102. The cubic root of 642815690 is about 863.0358230438.

It can be divided in two parts, 6428156 and 90, that added together give a palindrome (6428246).

The spelling of 642815690 in words is "six hundred forty-two million, eight hundred fifteen thousand, six hundred ninety".