861921 has 12 divisors (see below), whose sum is σ = 1291472. Its totient is φ = 574452.

The previous prime is 861907. The next prime is 861929. The reversal of 861921 is 129168.

861921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 861921 - 2⁶ = 861857 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (861929) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1531 + ... + 2016.

2⁸⁶¹⁹²¹ is an apocalyptic number.

861921 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

It is an amenable number.

861921 is a deficient number, since it is larger than the sum of its proper divisors (429551).

861921 is an equidigital number, since it uses as much as digits as its factorization.

861921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3562 (or 3550 counting only the distinct ones).

The product of its digits is 864, while the sum is 27.

The square root of 861921 is about 928.3970055962. The cubic root of 861921 is about 95.1676080863.

The spelling of 861921 in words is "eight hundred sixty-one thousand, nine hundred twenty-one".