661394400 has 72 divisors (see below), whose sum is σ = 2152846584. Its totient is φ = 176371200.

The previous prime is 661394341. The next prime is 661394429. The reversal of 661394400 is 4493166.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 135391 + ... + 140190.

It is an arithmetic number, because the mean of its divisors is an integer number (29900647).

Almost surely, 2^661394400 is an apocalyptic number.

661394400 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

661394400 is an abundant number, since it is smaller than the sum of its proper divisors (1491452184).

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

661394400 is a wasteful number, since it uses less digits than its factorization.

661394400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 275604 (or 275591 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 33.

The square root of 661394400 is about 25717.5893115976. The cubic root of 661394400 is about 871.2714926561.

The spelling of 661394400 in words is "six hundred sixty-one million, three hundred ninety-four thousand, four hundred".