225721645 has 16 divisors (see below), whose sum is σ = 287786160. Its totient is φ = 169634304.

The previous prime is 225721637. The next prime is 225721651. The reversal of 225721645 is 546127522.

It can be written as a sum of positive squares in 8 ways, for example, as 4247721 + 221473924 = 2061^2 + 14882^2 .

It is a cyclic number.

It is not a de Polignac number, because 225721645 - 2³ = 225721637 is a prime.

It is a super-3 number, since 3×225721645³ (a number of 26 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a self number, because there is not a number n which added to its sum of digits gives 225721645.

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, 15672 + ... + 26401.

It is an arithmetic number, because the mean of its divisors is an integer number (17986635).

Almost surely, 2^225721645 is an apocalyptic number.

It is an amenable number.

225721645 is a deficient number, since it is larger than the sum of its proper divisors (62064515).

225721645 is a wasteful number, since it uses less digits than its factorization.

225721645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42144.

The product of its digits is 33600, while the sum is 34.

The square root of 225721645 is about 15024.0355763690. The cubic root of 225721645 is about 608.8697560762.

The spelling of 225721645 in words is "two hundred twenty-five million, seven hundred twenty-one thousand, six hundred forty-five".