661807804 has 48 divisors (see below), whose sum is σ = 1346623488. Its totient is φ = 278739648.

The previous prime is 661807771. The next prime is 661807823. The reversal of 661807804 is 408708166.

It is a congruent number.

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, 517614 + ... + 518890.

It is an arithmetic number, because the mean of its divisors is an integer number (28054656).

Almost surely, 2^661807804 is an apocalyptic number.

It is an amenable number.

661807804 is an abundant number, since it is smaller than the sum of its proper divisors (684815684).

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

661807804 is a wasteful number, since it uses less digits than its factorization.

661807804 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1594 (or 1592 counting only the distinct ones).

The product of its (nonzero) digits is 64512, while the sum is 40.

The square root of 661807804 is about 25725.6254345740. The cubic root of 661807804 is about 871.4529840130.

It can be divided in two parts, 66180 and 7804, that added together give a square (73984 = 272²).

The spelling of 661807804 in words is "six hundred sixty-one million, eight hundred seven thousand, eight hundred four".