661964406 has 16 divisors (see below), whose sum is σ = 1324254144. Its totient is φ = 220600584.

The previous prime is 661964371. The next prime is 661964419. The reversal of 661964406 is 604469166.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18861 + ... + 40983.

It is an arithmetic number, because the mean of its divisors is an integer number (82765884).

Almost surely, 2^661964406 is an apocalyptic number.

661964406 is an abundant number, since it is smaller than the sum of its proper divisors (662289738).

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

661964406 is a wasteful number, since it uses less digits than its factorization.

661964406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27115.

The product of its (nonzero) digits is 186624, while the sum is 42.

The square root of 661964406 is about 25728.6689511914. The cubic root of 661964406 is about 871.5217152048.

The spelling of 661964406 in words is "six hundred sixty-one million, nine hundred sixty-four thousand, four hundred six".