661561523 has 8 divisors (see below), whose sum is σ = 756403200. Its totient is φ = 566803080.

The previous prime is 661561507. The next prime is 661561541. The reversal of 661561523 is 325165166.

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 661561523 - 2⁴ = 661561507 is a prime.

It is not an unprimeable number, because it can be changed into a prime (661561573) 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, 2723 + ... + 36476.

It is an arithmetic number, because the mean of its divisors is an integer number (94550400).

Almost surely, 2^661561523 is an apocalyptic number.

661561523 is a deficient number, since it is larger than the sum of its proper divisors (94841677).

661561523 is a wasteful number, since it uses less digits than its factorization.

661561523 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41617.

The product of its digits is 32400, while the sum is 35.

The square root of 661561523 is about 25720.8383028236. The cubic root of 661561523 is about 871.3448715875.

The spelling of 661561523 in words is "six hundred sixty-one million, five hundred sixty-one thousand, five hundred twenty-three".