642090906 has 12 divisors (see below), whose sum is σ = 1391197002. Its totient is φ = 214030296.

The previous prime is 642090893. The next prime is 642090913. The reversal of 642090906 is 609090246.

642090906 is a `hidden beast` number, since 642 + 0 + 9 + 0 + 9 + 0 + 6 = 666.

It can be written as a sum of positive squares in only one way, i.e., 486864225 + 155226681 = 22065^2 + 12459^2 .

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 17835841 + ... + 17835876.

Almost surely, 2^642090906 is an apocalyptic number.

642090906 is an abundant number, since it is smaller than the sum of its proper divisors (749106096).

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

642090906 is a wasteful number, since it uses less digits than its factorization.

642090906 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35671725 (or 35671722 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 36.

The square root of 642090906 is about 25339.5127419609. The cubic root of 642090906 is about 862.7113392634.

The spelling of 642090906 in words is "six hundred forty-two million, ninety thousand, nine hundred six".