661694280 has 64 divisors (see below), whose sum is σ = 2137786560. Its totient is φ = 162878208.

The previous prime is 661694261. The next prime is 661694309. The reversal of 661694280 is 82496166.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 210522 + ... + 213641.

It is an arithmetic number, because the mean of its divisors is an integer number (33402915).

Almost surely, 2^661694280 is an apocalyptic number.

661694280 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

661694280 is an abundant number, since it is smaller than the sum of its proper divisors (1476092280).

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

661694280 is a wasteful number, since it uses less digits than its factorization.

661694280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 424190 (or 424186 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 42.

The square root of 661694280 is about 25723.4189018490. The cubic root of 661694280 is about 871.4031525840.

The spelling of 661694280 in words is "six hundred sixty-one million, six hundred ninety-four thousand, two hundred eighty".