861720249 has 16 divisors (see below), whose sum is σ = 1241956800. Its totient is φ = 528311616.

The previous prime is 861720217. The next prime is 861720253. The reversal of 861720249 is 942027168.

It is not a de Polignac number, because 861720249 - 2⁵ = 861720217 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is not an unprimeable number, because it can be changed into a prime (861720049) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 30579 + ... + 51560.

It is an arithmetic number, because the mean of its divisors is an integer number (77622300).

Almost surely, 2^861720249 is an apocalyptic number.

It is an amenable number.

861720249 is a deficient number, since it is larger than the sum of its proper divisors (380236551).

861720249 is a wasteful number, since it uses less digits than its factorization.

861720249 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82424.

The product of its (nonzero) digits is 48384, while the sum is 39.

The square root of 861720249 is about 29355.0719467693. The cubic root of 861720249 is about 951.6021898070.

The spelling of 861720249 in words is "eight hundred sixty-one million, seven hundred twenty thousand, two hundred forty-nine".