661919874 has 128 divisors (see below), whose sum is σ = 1723023360. Its totient is φ = 164505600.

The previous prime is 661919861. The next prime is 661919893. The reversal of 661919874 is 478919166.

It is a happy number.

Its product of digits (653184) is a multiple of the sum of its prime divisors (576).

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1618182 + ... + 1618590.

It is an arithmetic number, because the mean of its divisors is an integer number (13461120).

Almost surely, 2^661919874 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661919874, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (861511680).

661919874 is an abundant number, since it is smaller than the sum of its proper divisors (1061103486).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661919874 is a wasteful number, since it uses less digits than its factorization.

661919874 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 576.

The product of its digits is 653184, while the sum is 51.

The square root of 661919874 is about 25727.8035207050. The cubic root of 661919874 is about 871.5021716185.

The spelling of 661919874 in words is "six hundred sixty-one million, nine hundred nineteen thousand, eight hundred seventy-four".