221555631 has 16 divisors (see below), whose sum is σ = 324247680. Its totient is φ = 133449120.

The previous prime is 221555617. The next prime is 221555647. The reversal of 221555631 is 136555122.

It is a happy number.

It is not a de Polignac number, because 221555631 - 2⁶ = 221555567 is a prime.

It is a super-2 number, since 2×221555631² = 98173795255616322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221555681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15216 + ... + 25973.

It is an arithmetic number, because the mean of its divisors is an integer number (20265480).

Almost surely, 2^221555631 is an apocalyptic number.

221555631 is a deficient number, since it is larger than the sum of its proper divisors (102692049).

221555631 is a wasteful number, since it uses less digits than its factorization.

221555631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41366.

The product of its digits is 9000, while the sum is 30.

The square root of 221555631 is about 14884.7449087984. The cubic root of 221555631 is about 605.1006193780.

The spelling of 221555631 in words is "two hundred twenty-one million, five hundred fifty-five thousand, six hundred thirty-one".