20995891 has 8 divisors (see below), whose sum is σ = 24121184. Its totient is φ = 17902080.

The previous prime is 20995889. The next prime is 20995903. The reversal of 20995891 is 19859902.

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

It is not a de Polignac number, because 20995891 - 2¹ = 20995889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20995831) 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, 6420 + ... + 9121.

It is an arithmetic number, because the mean of its divisors is an integer number (3015148).

Almost surely, 2^20995891 is an apocalyptic number.

20995891 is a deficient number, since it is larger than the sum of its proper divisors (3125293).

20995891 is a wasteful number, since it uses less digits than its factorization.

20995891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15741.

The product of its (nonzero) digits is 58320, while the sum is 43.

The square root of 20995891 is about 4582.1273443675. The cubic root of 20995891 is about 275.8744221478.

It can be divided in two parts, 209 and 95891, that added together give a square (96100 = 310²).

The spelling of 20995891 in words is "twenty million, nine hundred ninety-five thousand, eight hundred ninety-one".