21642189 has 4 divisors (see below), whose sum is σ = 28856256. Its totient is φ = 14428124.

The previous prime is 21642169. The next prime is 21642191. The reversal of 21642189 is 98124612.

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 21642189 - 2⁸ = 21641933 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21642119) 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, 3607029 + ... + 3607034.

It is an arithmetic number, because the mean of its divisors is an integer number (7214064).

Almost surely, 2^21642189 is an apocalyptic number.

It is an amenable number.

21642189 is a deficient number, since it is larger than the sum of its proper divisors (7214067).

21642189 is an equidigital number, since it uses as much as digits as its factorization.

21642189 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7214066.

The product of its digits is 6912, while the sum is 33.

The square root of 21642189 is about 4652.1166150474. The cubic root of 21642189 is about 278.6765306051.

The spelling of 21642189 in words is "twenty-one million, six hundred forty-two thousand, one hundred eighty-nine".