661076388 has 72 divisors (see below), whose sum is σ = 1927703232. Its totient is φ = 187106112.

The previous prime is 661076371. The next prime is 661076407. The reversal of 661076388 is 883670166.

661076388 is a `hidden beast` number, since 6 + 6 + 1 + 0 + 7 + 638 + 8 = 666.

It is a super-2 number, since 2×661076388² = 874043981542253088, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 14706 + ... + 39222.

It is an arithmetic number, because the mean of its divisors is an integer number (26773656).

Almost surely, 2^661076388 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 661076388, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (963851616).

661076388 is an abundant number, since it is smaller than the sum of its proper divisors (1266626844).

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

661076388 is a wasteful number, since it uses less digits than its factorization.

661076388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24641 (or 24636 counting only the distinct ones).

The product of its (nonzero) digits is 290304, while the sum is 45.

The square root of 661076388 is about 25711.4057958720. The cubic root of 661076388 is about 871.1318285315.

The spelling of 661076388 in words is "six hundred sixty-one million, seventy-six thousand, three hundred eighty-eight".