661990393 has 8 divisors (see below), whose sum is σ = 691815168. Its totient is φ = 632252544.

The previous prime is 661990349. The next prime is 661990397. The reversal of 661990393 is 393099166.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 661990393 - 2¹³ = 661982201 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661990397) by changing a digit.

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, 5905 + ... + 36862.

It is an arithmetic number, because the mean of its divisors is an integer number (86476896).

Almost surely, 2^661990393 is an apocalyptic number.

It is an amenable number.

661990393 is a deficient number, since it is larger than the sum of its proper divisors (29824775).

661990393 is a wasteful number, since it uses less digits than its factorization.

661990393 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43463.

The product of its (nonzero) digits is 236196, while the sum is 46.

The square root of 661990393 is about 25729.1739665307. The cubic root of 661990393 is about 871.5331196138.

The spelling of 661990393 in words is "six hundred sixty-one million, nine hundred ninety thousand, three hundred ninety-three".