21642091 has 8 divisors (see below), whose sum is σ = 22697280. Its totient is φ = 20607552.

The previous prime is 21642067. The next prime is 21642107. The reversal of 21642091 is 19024612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21642091 - 2⁹ = 21641579 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21642191) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2995 + ... + 7228.

It is an arithmetic number, because the mean of its divisors is an integer number (2837160).

Almost surely, 2^21642091 is an apocalyptic number.

21642091 is a deficient number, since it is larger than the sum of its proper divisors (1055189).

21642091 is a wasteful number, since it uses less digits than its factorization.

21642091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10325.

The product of its (nonzero) digits is 864, while the sum is 25.

The square root of 21642091 is about 4652.1060821955. The cubic root of 21642091 is about 278.6761099708.

The spelling of 21642091 in words is "twenty-one million, six hundred forty-two thousand, ninety-one".