861921783 has 8 divisors (see below), whose sum is σ = 1276921200. Its totient is φ = 574614504.

The previous prime is 861921773. The next prime is 861921791. The reversal of 861921783 is 387129168.

861921783 is a `hidden beast` number, since 8 + 619 + 21 + 7 + 8 + 3 = 666.

It is not a de Polignac number, because 861921783 - 2⁹ = 861921271 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (861921773) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15961488 + ... + 15961541.

It is an arithmetic number, because the mean of its divisors is an integer number (159615150).

Almost surely, 2^861921783 is an apocalyptic number.

861921783 is a deficient number, since it is larger than the sum of its proper divisors (414999417).

861921783 is a wasteful number, since it uses less digits than its factorization.

861921783 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31923038 (or 31923032 counting only the distinct ones).

The product of its digits is 145152, while the sum is 45.

The square root of 861921783 is about 29358.5044407919. The cubic root of 861921783 is about 951.6763690421.

The spelling of 861921783 in words is "eight hundred sixty-one million, nine hundred twenty-one thousand, seven hundred eighty-three".