20879191 has 4 divisors (see below), whose sum is σ = 21273192. Its totient is φ = 20485192.

The previous prime is 20879167. The next prime is 20879203. The reversal of 20879191 is 19197802.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20879191 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 20879191.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20879161) 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, 196921 + ... + 197026.

It is an arithmetic number, because the mean of its divisors is an integer number (5318298).

Almost surely, 2^20879191 is an apocalyptic number.

20879191 is a deficient number, since it is larger than the sum of its proper divisors (394001).

20879191 is an equidigital number, since it uses as much as digits as its factorization.

20879191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 394000.

The product of its (nonzero) digits is 9072, while the sum is 37.

The square root of 20879191 is about 4569.3753402407. The cubic root of 20879191 is about 275.3623476952.

It can be divided in two parts, 208791 and 91, that multiplied together give a palindrome (18999981).

The spelling of 20879191 in words is "twenty million, eight hundred seventy-nine thousand, one hundred ninety-one".