2321991 has 12 divisors (see below), whose sum is σ = 3833232. Its totient is φ = 1326816.

The previous prime is 2321989. The next prime is 2321999. The reversal of 2321991 is 1991232.

It is not a de Polignac number, because 2321991 - 2¹ = 2321989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2321999) 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, 18366 + ... + 18491.

It is an arithmetic number, because the mean of its divisors is an integer number (319436).

2^2321991 is an apocalyptic number.

2321991 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

2321991 is a deficient number, since it is larger than the sum of its proper divisors (1511241).

2321991 is a wasteful number, since it uses less digits than its factorization.

2321991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36870 (or 36867 counting only the distinct ones).

The product of its digits is 972, while the sum is 27.

The square root of 2321991 is about 1523.8080587791. The cubic root of 2321991 is about 132.4199777876.

The spelling of 2321991 in words is "two million, three hundred twenty-one thousand, nine hundred ninety-one".