21299689 has 4 divisors (see below), whose sum is σ = 21379140. Its totient is φ = 21220240.

The previous prime is 21299687. The next prime is 21299701. The reversal of 21299689 is 98699212.

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

It can be written as a sum of positive squares in 2 ways, for example, as 5139289 + 16160400 = 2267^2 + 4020^2 .

It is a cyclic number.

It is not a de Polignac number, because 21299689 - 2¹ = 21299687 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21299687) 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, 39322 + ... + 39859.

It is an arithmetic number, because the mean of its divisors is an integer number (5344785).

Almost surely, 2^21299689 is an apocalyptic number.

It is an amenable number.

21299689 is a deficient number, since it is larger than the sum of its proper divisors (79451).

21299689 is an equidigital number, since it uses as much as digits as its factorization.

21299689 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79450.

The product of its digits is 139968, while the sum is 46.

The square root of 21299689 is about 4615.1586104922. The cubic root of 21299689 is about 277.1986350416.

The spelling of 21299689 in words is "twenty-one million, two hundred ninety-nine thousand, six hundred eighty-nine".