2637991 has 4 divisors (see below), whose sum is σ = 2677432. Its totient is φ = 2598552.

The previous prime is 2637983. The next prime is 2637997. The reversal of 2637991 is 1997362.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1997362 = 2 ⋅998681.

It is a cyclic number.

It is not a de Polignac number, because 2637991 - 2³ = 2637983 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 2637991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2637997) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19620 + ... + 19753.

It is an arithmetic number, because the mean of its divisors is an integer number (669358).

2^2637991 is an apocalyptic number.

2637991 is a deficient number, since it is larger than the sum of its proper divisors (39441).

2637991 is an equidigital number, since it uses as much as digits as its factorization.

2637991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39440.

The product of its digits is 20412, while the sum is 37.

The square root of 2637991 is about 1624.1893362536. The cubic root of 2637991 is about 138.1733975210.

The spelling of 2637991 in words is "two million, six hundred thirty-seven thousand, nine hundred ninety-one".