221660538 has 32 divisors (see below), whose sum is σ = 484747200. Its totient is φ = 67013760.

The previous prime is 221660513. The next prime is 221660539. The reversal of 221660538 is 835066122.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a junction number, because it is equal to n+sod(n) for n = 221660499 and 221660508.

It is not an unprimeable number, because it can be changed into a prime (221660539) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 26488 + ... + 33836.

It is an arithmetic number, because the mean of its divisors is an integer number (15148350).

Almost surely, 2^221660538 is an apocalyptic number.

221660538 is an abundant number, since it is smaller than the sum of its proper divisors (263086662).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

221660538 is a wasteful number, since it uses less digits than its factorization.

221660538 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7822.

The product of its (nonzero) digits is 17280, while the sum is 33.

The square root of 221660538 is about 14888.2684688314. The cubic root of 221660538 is about 605.1961097278.

The spelling of 221660538 in words is "two hundred twenty-one million, six hundred sixty thousand, five hundred thirty-eight".