661095864 has 256 divisors, whose sum is σ = 2286144000. Its totient is φ = 173905920.

The previous prime is 661095859. The next prime is 661095887. The reversal of 661095864 is 468590166.

661095864 is a `hidden beast` number, since 6 + 61 + 0 + 9 + 586 + 4 = 666.

It is a congruent number.

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, 524467 + ... + 525725.

It is an arithmetic number, because the mean of its divisors is an integer number (8930250).

Almost surely, 2^661095864 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661095864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1143072000).

661095864 is an abundant number, since it is smaller than the sum of its proper divisors (1625048136).

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

661095864 is a wasteful number, since it uses less digits than its factorization.

661095864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1315 (or 1305 counting only the distinct ones).

The product of its (nonzero) digits is 311040, while the sum is 45.

The square root of 661095864 is about 25711.7845355004. The cubic root of 661095864 is about 871.1403832650.

The spelling of 661095864 in words is "six hundred sixty-one million, ninety-five thousand, eight hundred sixty-four".