21955189 has 4 divisors (see below), whose sum is σ = 22113280. Its totient is φ = 21797100.

The previous prime is 21955187. The next prime is 21955217. The reversal of 21955189 is 98155912.

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 21955189 - 2¹ = 21955187 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 (21955187) 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, 78837 + ... + 79114.

It is an arithmetic number, because the mean of its divisors is an integer number (5528320).

Almost surely, 2^21955189 is an apocalyptic number.

It is an amenable number.

21955189 is a deficient number, since it is larger than the sum of its proper divisors (158091).

21955189 is a wasteful number, since it uses less digits than its factorization.

21955189 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 158090.

The product of its digits is 32400, while the sum is 40.

The square root of 21955189 is about 4685.6364562352. The cubic root of 21955189 is about 280.0135580170.

The spelling of 21955189 in words is "twenty-one million, nine hundred fifty-five thousand, one hundred eighty-nine".