221660631 has 40 divisors (see below), whose sum is σ = 353503920. Its totient is φ = 138008448.

The previous prime is 221660627. The next prime is 221660639. The reversal of 221660631 is 136066122.

221660631 is a `hidden beast` number, since 2 + 21 + 6 + 6 + 0 + 631 = 666.

It is not a de Polignac number, because 221660631 - 2² = 221660627 is a prime.

It is a super-2 number, since 2×221660631² = 98266870670636322, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 221660595 and 221660604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221660639) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 111361 + ... + 113333.

It is an arithmetic number, because the mean of its divisors is an integer number (8837598).

Almost surely, 2^221660631 is an apocalyptic number.

221660631 is a deficient number, since it is larger than the sum of its proper divisors (131843289).

221660631 is a wasteful number, since it uses less digits than its factorization.

221660631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2077 (or 2068 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 27.

The square root of 221660631 is about 14888.2715920956. The cubic root of 221660631 is about 605.1961943666.

The spelling of 221660631 in words is "two hundred twenty-one million, six hundred sixty thousand, six hundred thirty-one".