661958783 has 4 divisors (see below), whose sum is σ = 666342768. Its totient is φ = 657574800.

The previous prime is 661958743. The next prime is 661958807. The reversal of 661958783 is 387859166.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 661958783 - 2¹⁰ = 661957759 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661958743) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2191766 + ... + 2192067.

It is an arithmetic number, because the mean of its divisors is an integer number (166585692).

Almost surely, 2^661958783 is an apocalyptic number.

661958783 is a deficient number, since it is larger than the sum of its proper divisors (4383985).

661958783 is a wasteful number, since it uses less digits than its factorization.

661958783 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4383984.

The product of its digits is 2177280, while the sum is 53.

The square root of 661958783 is about 25728.5596759710. The cubic root of 661958783 is about 871.5192475089.

The spelling of 661958783 in words is "six hundred sixty-one million, nine hundred fifty-eight thousand, seven hundred eighty-three".