664553861 has 4 divisors (see below), whose sum is σ = 699530400. Its totient is φ = 629577324.

The previous prime is 664553843. The next prime is 664553873. The reversal of 664553861 is 168355466.

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-664553861 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 (664553801) 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, 17488241 + ... + 17488278.

It is an arithmetic number, because the mean of its divisors is an integer number (174882600).

Almost surely, 2^664553861 is an apocalyptic number.

It is an amenable number.

664553861 is a deficient number, since it is larger than the sum of its proper divisors (34976539).

664553861 is a wasteful number, since it uses less digits than its factorization.

664553861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34976538.

The product of its digits is 518400, while the sum is 44.

The square root of 664553861 is about 25778.9422009515. The cubic root of 664553861 is about 872.6566352337.

It can be divided in two parts, 6645 and 53861, that added together give a palindrome (60506).

The spelling of 664553861 in words is "six hundred sixty-four million, five hundred fifty-three thousand, eight hundred sixty-one".