20149921 has 4 divisors (see below), whose sum is σ = 21981744. Its totient is φ = 18318100.

The previous prime is 20149891. The next prime is 20149931. The reversal of 20149921 is 12994102.

It is a happy number.

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 20149921 - 2⁵ = 20149889 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 20149921.

It is not an unprimeable number, because it can be changed into a prime (20149931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 915895 + ... + 915916.

It is an arithmetic number, because the mean of its divisors is an integer number (5495436).

Almost surely, 2^20149921 is an apocalyptic number.

It is an amenable number.

20149921 is a deficient number, since it is larger than the sum of its proper divisors (1831823).

20149921 is a wasteful number, since it uses less digits than its factorization.

20149921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1831822.

The product of its (nonzero) digits is 1296, while the sum is 28.

The square root of 20149921 is about 4488.8663379522. The cubic root of 20149921 is about 272.1183209634.

It can be divided in two parts, 2014 and 9921, that added together give a triangular number (11935 = T₁₅₄).

The spelling of 20149921 in words is "twenty million, one hundred forty-nine thousand, nine hundred twenty-one".