521990642 has 4 divisors (see below), whose sum is σ = 782985966. Its totient is φ = 260995320.

The previous prime is 521990611. The next prime is 521990647. The reversal of 521990642 is 246099125.

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

It can be written as a sum of positive squares in only one way, i.e., 351975121 + 170015521 = 18761^2 + 13039^2 .

It is a junction number, because it is equal to n+sod(n) for n = 521990596 and 521990605.

It is not an unprimeable number, because it can be changed into a prime (521990647) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130497659 + ... + 130497662.

Almost surely, 2^521990642 is an apocalyptic number.

521990642 is a deficient number, since it is larger than the sum of its proper divisors (260995324).

521990642 is a wasteful number, since it uses less digits than its factorization.

521990642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 260995323.

The product of its (nonzero) digits is 38880, while the sum is 38.

The square root of 521990642 is about 22847.1145224074. The cubic root of 521990642 is about 805.1699765805.

The spelling of 521990642 in words is "five hundred twenty-one million, nine hundred ninety thousand, six hundred forty-two".