21798591 has 4 divisors (see below), whose sum is σ = 29064792. Its totient is φ = 14532392.

The previous prime is 21798571. The next prime is 21798599. The reversal of 21798591 is 19589712.

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

It is a cyclic number.

It is not a de Polignac number, because 21798591 - 2⁵ = 21798559 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21798599) 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, 3633096 + ... + 3633101.

It is an arithmetic number, because the mean of its divisors is an integer number (7266198).

Almost surely, 2^21798591 is an apocalyptic number.

21798591 is a deficient number, since it is larger than the sum of its proper divisors (7266201).

21798591 is an equidigital number, since it uses as much as digits as its factorization.

21798591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7266200.

The product of its digits is 45360, while the sum is 42.

The square root of 21798591 is about 4668.8961222113. The cubic root of 21798591 is about 279.3462255347.

The spelling of 21798591 in words is "twenty-one million, seven hundred ninety-eight thousand, five hundred ninety-one".