661606637 has 8 divisors (see below), whose sum is σ = 666754200. Its totient is φ = 656468800.

The previous prime is 661606607. The next prime is 661606679. The reversal of 661606637 is 736606166.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 3632836 + 657973801 = 1906^2 + 25651^2 .

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 661606637 - 2²⁰ = 660558061 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 661606594 and 661606603.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661606607) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 192143 + ... + 195555.

It is an arithmetic number, because the mean of its divisors is an integer number (83344275).

Almost surely, 2^661606637 is an apocalyptic number.

It is an amenable number.

661606637 is a deficient number, since it is larger than the sum of its proper divisors (5147563).

661606637 is a wasteful number, since it uses less digits than its factorization.

661606637 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4863.

The product of its (nonzero) digits is 163296, while the sum is 41.

The square root of 661606637 is about 25721.7152810616. The cubic root of 661606637 is about 871.3646777369.

The spelling of 661606637 in words is "six hundred sixty-one million, six hundred six thousand, six hundred thirty-seven".