21089311 has 4 divisors (see below), whose sum is σ = 21231000. Its totient is φ = 20947624.

The previous prime is 21089291. The next prime is 21089359. The reversal of 21089311 is 11398012.

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 21089311 - 2⁹ = 21088799 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 (21089381) 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, 70621 + ... + 70918.

It is an arithmetic number, because the mean of its divisors is an integer number (5307750).

Almost surely, 2^21089311 is an apocalyptic number.

21089311 is a deficient number, since it is larger than the sum of its proper divisors (141689).

21089311 is a wasteful number, since it uses less digits than its factorization.

21089311 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 141688.

The product of its (nonzero) digits is 432, while the sum is 25.

The square root of 21089311 is about 4592.3099851817. The cubic root of 21089311 is about 276.2829792121.

The spelling of 21089311 in words is "twenty-one million, eighty-nine thousand, three hundred eleven".