861978993 has 4 divisors (see below), whose sum is σ = 1149305328. Its totient is φ = 574652660.

The previous prime is 861978959. The next prime is 861979003. The reversal of 861978993 is 399879168.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 861978993 - 2¹⁴ = 861962609 is a prime.

It is not an unprimeable number, because it can be changed into a prime (861978493) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 143663163 + ... + 143663168.

It is an arithmetic number, because the mean of its divisors is an integer number (287326332).

Almost surely, 2^861978993 is an apocalyptic number.

It is an amenable number.

861978993 is a deficient number, since it is larger than the sum of its proper divisors (287326335).

861978993 is a wasteful number, since it uses less digits than its factorization.

861978993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 287326334.

The product of its digits is 5878656, while the sum is 60.

The square root of 861978993 is about 29359.4787589971. The cubic root of 861978993 is about 951.6974243945.

The spelling of 861978993 in words is "eight hundred sixty-one million, nine hundred seventy-eight thousand, nine hundred ninety-three".