20811901 has 4 divisors (see below), whose sum is σ = 22703904. Its totient is φ = 18919900.

The previous prime is 20811899. The next prime is 20811907. The reversal of 20811901 is 10911802.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20811901 - 2¹ = 20811899 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20811907) 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, 945985 + ... + 946006.

It is an arithmetic number, because the mean of its divisors is an integer number (5675976).

Almost surely, 2^20811901 is an apocalyptic number.

It is an amenable number.

20811901 is a deficient number, since it is larger than the sum of its proper divisors (1892003).

20811901 is a wasteful number, since it uses less digits than its factorization.

20811901 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1892002.

The product of its (nonzero) digits is 144, while the sum is 22.

The square root of 20811901 is about 4562.0062472557. The cubic root of 20811901 is about 275.0662143587.

Subtracting from 20811901 its reverse (10911802), we obtain a palindrome (9900099).

It can be divided in two parts, 20811 and 901, that added together give a palindrome (21712).

The spelling of 20811901 in words is "twenty million, eight hundred eleven thousand, nine hundred one".