721161655 has 16 divisors (see below), whose sum is σ = 889703424. Its totient is φ = 560887200.

The previous prime is 721161583. The next prime is 721161667. The reversal of 721161655 is 556161127.

It is a de Polignac number, because none of the positive numbers 2^k-721161655 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 721161655.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 25324 + ... + 45646.

It is an arithmetic number, because the mean of its divisors is an integer number (55606464).

Almost surely, 2^721161655 is an apocalyptic number.

721161655 is a deficient number, since it is larger than the sum of its proper divisors (168541769).

721161655 is a wasteful number, since it uses less digits than its factorization.

721161655 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20526.

The product of its digits is 12600, while the sum is 34.

The square root of 721161655 is about 26854.4531688880. The cubic root of 721161655 is about 896.7627131093.

The spelling of 721161655 in words is "seven hundred twenty-one million, one hundred sixty-one thousand, six hundred fifty-five".