721137818642 has 4 divisors (see below), whose sum is σ = 1081706727966. Its totient is φ = 360568909320.

The previous prime is 721137818617. The next prime is 721137818683. The reversal of 721137818642 is 246818731127.

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., 452752691161 + 268385127481 = 672869^2 + 518059^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 180284454659 + ... + 180284454662.

Almost surely, 2^721137818642 is an apocalyptic number.

721137818642 is a deficient number, since it is larger than the sum of its proper divisors (360568909324).

721137818642 is a wasteful number, since it uses less digits than its factorization.

721137818642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 360568909323.

The product of its digits is 903168, while the sum is 50.

The spelling of 721137818642 in words is "seven hundred twenty-one billion, one hundred thirty-seven million, eight hundred eighteen thousand, six hundred forty-two".