2123991 has 12 divisors (see below), whose sum is σ = 3229720. Its totient is φ = 1341360.

The previous prime is 2123983. The next prime is 2123999. The reversal of 2123991 is 1993212.

It is an interprime number because it is at equal distance from previous prime (2123983) and next prime (2123999).

It is not a de Polignac number, because 2123991 - 2³ = 2123983 is a prime.

It is a super-2 number, since 2×2123991² = 9022675536162, which contains 22 as substring.

It is a d-powerful number, because it can be written as 2⁹ + 1 + 2²¹ + 3⁹ + 9² + 9⁴ + 1 .

It is a Duffinian number.

2123991 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2123999) 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, 6040 + ... + 6381.

2^2123991 is an apocalyptic number.

2123991 is a deficient number, since it is larger than the sum of its proper divisors (1105729).

2123991 is a wasteful number, since it uses less digits than its factorization.

2123991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12446 (or 12443 counting only the distinct ones).

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

The square root of 2123991 is about 1457.3918484745. The cubic root of 2123991 is about 128.5437278948.

The spelling of 2123991 in words is "two million, one hundred twenty-three thousand, nine hundred ninety-one".