661173639 has 32 divisors (see below), whose sum is σ = 1103569920. Its totient is φ = 343322112.

The previous prime is 661173599. The next prime is 661173661. The reversal of 661173639 is 936371166.

It is not a de Polignac number, because 661173639 - 2¹¹ = 661171591 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 661173639.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661173439) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 21579 + ... + 42284.

It is an arithmetic number, because the mean of its divisors is an integer number (34486560).

Almost surely, 2^661173639 is an apocalyptic number.

661173639 is a deficient number, since it is larger than the sum of its proper divisors (442396281).

661173639 is a wasteful number, since it uses less digits than its factorization.

661173639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63919.

The product of its digits is 122472, while the sum is 42.

The square root of 661173639 is about 25713.2969297988. The cubic root of 661173639 is about 871.1745438612.

The spelling of 661173639 in words is "six hundred sixty-one million, one hundred seventy-three thousand, six hundred thirty-nine".