221651172 has 18 divisors (see below), whose sum is σ = 560284998. Its totient is φ = 73883712.

The previous prime is 221651167. The next prime is 221651179. The reversal of 221651172 is 271156122.

221651172 is a `hidden beast` number, since 2 + 2 + 1 + 651 + 1 + 7 + 2 = 666.

It can be written as a sum of positive squares in only one way, i.e., 195272676 + 26378496 = 13974^2 + 5136^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is not an unprimeable number, because it can be changed into a prime (221651179) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3078453 + ... + 3078524.

Almost surely, 2^221651172 is an apocalyptic number.

It is an amenable number.

221651172 is an abundant number, since it is smaller than the sum of its proper divisors (338633826).

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

221651172 is a wasteful number, since it uses less digits than its factorization.

221651172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6156987 (or 6156982 counting only the distinct ones).

The product of its digits is 1680, while the sum is 27.

The square root of 221651172 is about 14887.9539225509. The cubic root of 221651172 is about 605.1875856626.

The spelling of 221651172 in words is "two hundred twenty-one million, six hundred fifty-one thousand, one hundred seventy-two".