20513891 has 2 divisors, whose sum is σ = 20513892. Its totient is φ = 20513890.

The previous prime is 20513879. The next prime is 20513897. The reversal of 20513891 is 19831502.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20513891 - 2⁶ = 20513827 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20513897) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10256945 + 10256946.

It is an arithmetic number, because the mean of its divisors is an integer number (10256946).

Almost surely, 2^20513891 is an apocalyptic number.

20513891 is a deficient number, since it is larger than the sum of its proper divisors (1).

20513891 is an equidigital number, since it uses as much as digits as its factorization.

20513891 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2160, while the sum is 29.

The square root of 20513891 is about 4529.2263136213. The cubic root of 20513891 is about 273.7469870327.

The spelling of 20513891 in words is "twenty million, five hundred thirteen thousand, eight hundred ninety-one".