661634593 has 4 divisors (see below), whose sum is σ = 677021488. Its totient is φ = 646247700.

The previous prime is 661634569. The next prime is 661634627. The reversal of 661634593 is 395436166.

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 a de Polignac number, because none of the positive numbers 2^k-661634593 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (43), and also a Moran number because the ratio is a prime number: 15386851 = 661634593 / (6 + 6 + 1 + 6 + 3 + 4 + 5 + 9 + 3).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661634293) 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, 7693383 + ... + 7693468.

It is an arithmetic number, because the mean of its divisors is an integer number (169255372).

Almost surely, 2^661634593 is an apocalyptic number.

It is an amenable number.

661634593 is a deficient number, since it is larger than the sum of its proper divisors (15386895).

661634593 is a wasteful number, since it uses less digits than its factorization.

661634593 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15386894.

The product of its digits is 349920, while the sum is 43.

The square root of 661634593 is about 25722.2587071975. The cubic root of 661634593 is about 871.3769506528.

It can be divided in two parts, 66163 and 4593, that added together give a square (70756 = 266²).

The spelling of 661634593 in words is "six hundred sixty-one million, six hundred thirty-four thousand, five hundred ninety-three".