221220915 has 32 divisors (see below), whose sum is σ = 376923456. Its totient is φ = 110407680.

The previous prime is 221220907. The next prime is 221220931. The reversal of 221220915 is 519022122.

221220915 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 221220915 - 2³ = 221220907 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 43759 + ... + 48551.

It is an arithmetic number, because the mean of its divisors is an integer number (11778858).

Almost surely, 2^221220915 is an apocalyptic number.

221220915 is a deficient number, since it is larger than the sum of its proper divisors (155702541).

221220915 is a wasteful number, since it uses less digits than its factorization.

221220915 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4999.

The product of its (nonzero) digits is 720, while the sum is 24.

The square root of 221220915 is about 14873.4970669308. The cubic root of 221220915 is about 604.7957464541.

The spelling of 221220915 in words is "two hundred twenty-one million, two hundred twenty thousand, nine hundred fifteen".