661359251 has 4 divisors (see below), whose sum is σ = 755839152. Its totient is φ = 566879352.

The previous prime is 661359241. The next prime is 661359263. The reversal of 661359251 is 152953166.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 661359251 - 2¹⁰ = 661358227 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661359241) 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, 47239940 + ... + 47239953.

It is an arithmetic number, because the mean of its divisors is an integer number (188959788).

Almost surely, 2^661359251 is an apocalyptic number.

661359251 is a deficient number, since it is larger than the sum of its proper divisors (94479901).

661359251 is an equidigital number, since it uses as much as digits as its factorization.

661359251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94479900.

The product of its digits is 48600, while the sum is 38.

The square root of 661359251 is about 25716.9059375346. The cubic root of 661359251 is about 871.2560581618.

The spelling of 661359251 in words is "six hundred sixty-one million, three hundred fifty-nine thousand, two hundred fifty-one".