661506394 has 16 divisors (see below), whose sum is σ = 1054072800. Its totient is φ = 310468464.

The previous prime is 661506383. The next prime is 661506401. The reversal of 661506394 is 493605166.

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, 75712 + ... + 83995.

It is an arithmetic number, because the mean of its divisors is an integer number (65879550).

Almost surely, 2^661506394 is an apocalyptic number.

661506394 is a deficient number, since it is larger than the sum of its proper divisors (392566406).

661506394 is a wasteful number, since it uses less digits than its factorization.

661506394 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 159837.

The product of its (nonzero) digits is 116640, while the sum is 40.

The square root of 661506394 is about 25719.7666008072. The cubic root of 661506394 is about 871.3206673858.

The spelling of 661506394 in words is "six hundred sixty-one million, five hundred six thousand, three hundred ninety-four".