21923149 has 4 divisors (see below), whose sum is σ = 23212764. Its totient is φ = 20633536.

The previous prime is 21923147. The next prime is 21923173. The reversal of 21923149 is 94132912.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 16892100 + 5031049 = 4110^2 + 2243^2 .

It is a cyclic number.

It is not a de Polignac number, because 21923149 - 2¹ = 21923147 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 21923149.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21923147) 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, 644782 + ... + 644815.

It is an arithmetic number, because the mean of its divisors is an integer number (5803191).

Almost surely, 2^21923149 is an apocalyptic number.

It is an amenable number.

21923149 is a deficient number, since it is larger than the sum of its proper divisors (1289615).

21923149 is a wasteful number, since it uses less digits than its factorization.

21923149 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1289614.

The product of its digits is 3888, while the sum is 31.

The square root of 21923149 is about 4682.2162487438. The cubic root of 21923149 is about 279.8772804055.

The spelling of 21923149 in words is "twenty-one million, nine hundred twenty-three thousand, one hundred forty-nine".