20402091 has 16 divisors (see below), whose sum is σ = 32004000. Its totient is φ = 12801024.

The previous prime is 20402087. The next prime is 20402099. The reversal of 20402091 is 19020402.

It is not a de Polignac number, because 20402091 - 2² = 20402087 is a prime.

20402091 is a modest number, since divided by 2091 gives 204 as remainder.

It is not an unprimeable number, because it can be changed into a prime (20402099) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21766 + ... + 22683.

It is an arithmetic number, because the mean of its divisors is an integer number (2000250).

Almost surely, 2^20402091 is an apocalyptic number.

20402091 is a deficient number, since it is larger than the sum of its proper divisors (11601909).

20402091 is a wasteful number, since it uses less digits than its factorization.

20402091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44475 (or 44469 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 20402091 is about 4516.8673879139. The cubic root of 20402091 is about 273.2487769714.

Adding to 20402091 its reverse (19020402), we get a palindrome (39422493).

The spelling of 20402091 in words is "twenty million, four hundred two thousand, ninety-one".