661885913 has 8 divisors (see below), whose sum is σ = 727966848. Its totient is φ = 597971664.

The previous prime is 661885897. The next prime is 661885949. The reversal of 661885913 is 319588166.

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 661885913 - 2⁴ = 661885897 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (47).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661885993) 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, 541031 + ... + 542252.

It is an arithmetic number, because the mean of its divisors is an integer number (90995856).

Almost surely, 2^661885913 is an apocalyptic number.

It is an amenable number.

661885913 is a deficient number, since it is larger than the sum of its proper divisors (66080935).

661885913 is a wasteful number, since it uses less digits than its factorization.

661885913 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1083343.

The product of its digits is 311040, while the sum is 47.

The square root of 661885913 is about 25727.1435064214. The cubic root of 661885913 is about 871.4872666970.

The spelling of 661885913 in words is "six hundred sixty-one million, eight hundred eighty-five thousand, nine hundred thirteen".