21726087 has 4 divisors (see below), whose sum is σ = 28968120. Its totient is φ = 14484056.

The previous prime is 21726073. The next prime is 21726113. The reversal of 21726087 is 78062712.

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 21726087 - 2¹⁰ = 21725063 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21726587) 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, 3621012 + ... + 3621017.

It is an arithmetic number, because the mean of its divisors is an integer number (7242030).

Almost surely, 2^21726087 is an apocalyptic number.

21726087 is a deficient number, since it is larger than the sum of its proper divisors (7242033).

21726087 is an equidigital number, since it uses as much as digits as its factorization.

21726087 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7242032.

The product of its (nonzero) digits is 9408, while the sum is 33.

The square root of 21726087 is about 4661.1250787766. The cubic root of 21726087 is about 279.0361716184.

Adding to 21726087 its reverse (78062712), we get a palindrome (99788799).

The spelling of 21726087 in words is "twenty-one million, seven hundred twenty-six thousand, eighty-seven".