637561 has 4 divisors (see below), whose sum is σ = 652432. Its totient is φ = 622692.

The previous prime is 637543. The next prime is 637573. The reversal of 637561 is 165736.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 637561 - 2⁵ = 637529 is a prime.

It is a Duffinian number.

637561 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (637531) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7371 + ... + 7456.

It is an arithmetic number, because the mean of its divisors is an integer number (163108).

2⁶³⁷⁵⁶¹ is an apocalyptic number.

It is an amenable number.

637561 is a deficient number, since it is larger than the sum of its proper divisors (14871).

637561 is a wasteful number, since it uses less digits than its factorization.

637561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14870.

The product of its digits is 3780, while the sum is 28.

The square root of 637561 is about 798.4741699016. The cubic root of 637561 is about 86.0677760295.

The spelling of 637561 in words is "six hundred thirty-seven thousand, five hundred sixty-one".