661418990 has 16 divisors (see below), whose sum is σ = 1199121840. Its totient is φ = 262663680.

The previous prime is 661418977. The next prime is 661419019. The reversal of 661418990 is 99814166.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 236531 + ... + 239310.

It is an arithmetic number, because the mean of its divisors is an integer number (74945115).

Almost surely, 2^661418990 is an apocalyptic number.

661418990 is a deficient number, since it is larger than the sum of its proper divisors (537702850).

661418990 is a wasteful number, since it uses less digits than its factorization.

661418990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 475987.

The product of its (nonzero) digits is 93312, while the sum is 44.

The square root of 661418990 is about 25718.0673846228. The cubic root of 661418990 is about 871.2822901976.

The spelling of 661418990 in words is "six hundred sixty-one million, four hundred eighteen thousand, nine hundred ninety".