221655864 has 32 divisors (see below), whose sum is σ = 559858320. Its totient is φ = 73122816.

The previous prime is 221655857. The next prime is 221655869. The reversal of 221655864 is 468556122.

221655864 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221655869) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 45279 + ... + 49934.

Almost surely, 2^221655864 is an apocalyptic number.

221655864 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

221655864 is an abundant number, since it is smaller than the sum of its proper divisors (338202456).

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

221655864 is a wasteful number, since it uses less digits than its factorization.

221655864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 95319 (or 95315 counting only the distinct ones).

The product of its digits is 115200, while the sum is 39.

The square root of 221655864 is about 14888.1114987765. Note that the first 3 decimals coincide. The cubic root of 221655864 is about 605.1918559162.

It can be divided in two parts, 221 and 655864, that added together give a triangular number (656085 = T₁₁₄₅).

The spelling of 221655864 in words is "two hundred twenty-one million, six hundred fifty-five thousand, eight hundred sixty-four".