225637661 has 8 divisors (see below), whose sum is σ = 234257400. Its totient is φ = 217073920.

The previous prime is 225637649. The next prime is 225637663. The reversal of 225637661 is 166736522.

It can be written as a sum of positive squares in 4 ways, for example, as 13032100 + 212605561 = 3610^2 + 14581^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 225637661 - 2¹⁸ = 225375517 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (225637663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5696 + ... + 21993.

It is an arithmetic number, because the mean of its divisors is an integer number (29282175).

Almost surely, 2^225637661 is an apocalyptic number.

It is an amenable number.

225637661 is a deficient number, since it is larger than the sum of its proper divisors (8619739).

225637661 is a wasteful number, since it uses less digits than its factorization.

225637661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27999.

The product of its digits is 90720, while the sum is 38.

The square root of 225637661 is about 15021.2403282818. The cubic root of 225637661 is about 608.7942328791.

It can be divided in two parts, 2256376 and 61, that multiplied together give a triangular number (137638936 = T₁₆₅₉₁).

The spelling of 225637661 in words is "two hundred twenty-five million, six hundred thirty-seven thousand, six hundred sixty-one".