21798671 has 4 divisors (see below), whose sum is σ = 22168200. Its totient is φ = 21429144.

The previous prime is 21798653. The next prime is 21798683. The reversal of 21798671 is 17689712.

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 21798671 - 2¹⁸ = 21536527 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 (21798631) 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, 184676 + ... + 184793.

It is an arithmetic number, because the mean of its divisors is an integer number (5542050).

Almost surely, 2^21798671 is an apocalyptic number.

21798671 is a deficient number, since it is larger than the sum of its proper divisors (369529).

21798671 is an equidigital number, since it uses as much as digits as its factorization.

21798671 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 369528.

The product of its digits is 42336, while the sum is 41.

The square root of 21798671 is about 4668.9046895391. The cubic root of 21798671 is about 279.3465672643.

The spelling of 21798671 in words is "twenty-one million, seven hundred ninety-eight thousand, six hundred seventy-one".