221031645 has 16 divisors (see below), whose sum is σ = 354341952. Its totient is φ = 117653120.

The previous prime is 221031631. The next prime is 221031661. The reversal of 221031645 is 546130122.

It is not a de Polignac number, because 221031645 - 2¹⁷ = 220900573 is a prime.

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, 6327 + ... + 21956.

It is an arithmetic number, because the mean of its divisors is an integer number (22146372).

Almost surely, 2^221031645 is an apocalyptic number.

It is an amenable number.

221031645 is a deficient number, since it is larger than the sum of its proper divisors (133310307).

221031645 is a wasteful number, since it uses less digits than its factorization.

221031645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28812.

The product of its (nonzero) digits is 1440, while the sum is 24.

The square root of 221031645 is about 14867.1330457489. The cubic root of 221031645 is about 604.6232155219.

Adding to 221031645 its reverse (546130122), we get a palindrome (767161767).

The spelling of 221031645 in words is "two hundred twenty-one million, thirty-one thousand, six hundred forty-five".