221665620 has 48 divisors (see below), whose sum is σ = 677089728. Its totient is φ = 53736960.

The previous prime is 221665607. The next prime is 221665637. The reversal of 221665620 is 26566122.

221665620 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (30).

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, 167269 + ... + 168588.

It is an arithmetic number, because the mean of its divisors is an integer number (14106036).

Almost surely, 2^221665620 is an apocalyptic number.

221665620 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

221665620 is an abundant number, since it is smaller than the sum of its proper divisors (455424108).

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

221665620 is a wasteful number, since it uses less digits than its factorization.

221665620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 335880 (or 335878 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 30.

The square root of 221665620 is about 14888.4391391442. The cubic root of 221665620 is about 605.2007347927.

The spelling of 221665620 in words is "two hundred twenty-one million, six hundred sixty-five thousand, six hundred twenty".