20891047 has 2 divisors, whose sum is σ = 20891048. Its totient is φ = 20891046.

The previous prime is 20891041. The next prime is 20891071. The reversal of 20891047 is 74019802.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20891047 - 2²³ = 12502439 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20891041) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10445523 + 10445524.

It is an arithmetic number, because the mean of its divisors is an integer number (10445524).

Almost surely, 2^20891047 is an apocalyptic number.

20891047 is a deficient number, since it is larger than the sum of its proper divisors (1).

20891047 is an equidigital number, since it uses as much as digits as its factorization.

20891047 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4032, while the sum is 31.

The square root of 20891047 is about 4570.6724888139. The cubic root of 20891047 is about 275.4144582431.

It can be divided in two parts, 2089 and 1047, that added together give a square (3136 = 56²).

The spelling of 20891047 in words is "twenty million, eight hundred ninety-one thousand, forty-seven".