20253991 has 4 divisors (see below), whose sum is σ = 20341152. Its totient is φ = 20166832.

The previous prime is 20253979. The next prime is 20254009. The reversal of 20253991 is 19935202.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20253991 - 2²¹ = 18156839 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 (20253931) 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, 43231 + ... + 43696.

It is an arithmetic number, because the mean of its divisors is an integer number (5085288).

Almost surely, 2^20253991 is an apocalyptic number.

20253991 is a deficient number, since it is larger than the sum of its proper divisors (87161).

20253991 is an equidigital number, since it uses as much as digits as its factorization.

20253991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87160.

The product of its (nonzero) digits is 4860, while the sum is 31.

The square root of 20253991 is about 4500.4434225974. The cubic root of 20253991 is about 272.5859942382.

The spelling of 20253991 in words is "twenty million, two hundred fifty-three thousand, nine hundred ninety-one".