661209796 has 81 divisors (see below), whose sum is σ = 1340987949. Its totient is φ = 285116832.

The previous prime is 661209767. The next prime is 661209797. The reversal of 661209796 is 697902166.

The square root of 661209796 is 25714.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 97812100 + 563397696 = 9890^2 + 23736^2 .

It is a Harshad number since it is a multiple of its sum of digits (46).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661209797) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 15376951 + ... + 15376993.

Almost surely, 2^661209796 is an apocalyptic number.

661209796 is the 25714-th square number.

It is an amenable number.

661209796 is an abundant number, since it is smaller than the sum of its proper divisors (679778153).

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

661209796 is a wasteful number, since it uses less digits than its factorization.

661209796 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 162 (or 81 counting only the distinct ones).

The product of its (nonzero) digits is 244944, while the sum is 46.

The cubic root of 661209796 is about 871.1904239477.

The spelling of 661209796 in words is "six hundred sixty-one million, two hundred nine thousand, seven hundred ninety-six".