2563991 has 8 divisors (see below), whose sum is σ = 2773440. Its totient is φ = 2361088.

The previous prime is 2563969. The next prime is 2563997. The reversal of 2563991 is 1993652.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 2563991 - 2⁶ = 2563927 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2563997) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 806 + ... + 2403.

It is an arithmetic number, because the mean of its divisors is an integer number (346680).

2^2563991 is an apocalyptic number.

2563991 is a deficient number, since it is larger than the sum of its proper divisors (209449).

2563991 is a wasteful number, since it uses less digits than its factorization.

2563991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3273.

The product of its digits is 14580, while the sum is 35.

The square root of 2563991 is about 1601.2467017921. The cubic root of 2563991 is about 136.8691275116.

The spelling of 2563991 in words is "two million, five hundred sixty-three thousand, nine hundred ninety-one".