667636637 has 4 divisors (see below), whose sum is σ = 690658620. Its totient is φ = 644614656.

The previous prime is 667636609. The next prime is 667636639. The reversal of 667636637 is 736636766.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 736636766 = 2 ⋅368318383.

It can be written as a sum of positive squares in 2 ways, for example, as 362750116 + 304886521 = 19046^2 + 17461^2 .

It is a cyclic number.

It is not a de Polignac number, because 667636637 - 2¹⁶ = 667571101 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 (667636639) 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, 11510948 + ... + 11511005.

It is an arithmetic number, because the mean of its divisors is an integer number (172664655).

Almost surely, 2^667636637 is an apocalyptic number.

It is an amenable number.

667636637 is a deficient number, since it is larger than the sum of its proper divisors (23021983).

667636637 is a wasteful number, since it uses less digits than its factorization.

667636637 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23021982.

The product of its digits is 3429216, while the sum is 50.

The square root of 667636637 is about 25838.6655421676. The cubic root of 667636637 is about 874.0039329941.

The spelling of 667636637 in words is "six hundred sixty-seven million, six hundred thirty-six thousand, six hundred thirty-seven".