21052691 has 8 divisors (see below), whose sum is σ = 23171184. Its totient is φ = 18968320.

The previous prime is 21052687. The next prime is 21052709. The reversal of 21052691 is 19625012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21052691 - 2² = 21052687 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21052691.

It is not an unprimeable number, because it can be changed into a prime (21052621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7226 + ... + 9711.

It is an arithmetic number, because the mean of its divisors is an integer number (2896398).

Almost surely, 2^21052691 is an apocalyptic number.

21052691 is a deficient number, since it is larger than the sum of its proper divisors (2118493).

21052691 is a wasteful number, since it uses less digits than its factorization.

21052691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17061.

The product of its (nonzero) digits is 1080, while the sum is 26.

The square root of 21052691 is about 4588.3211526658. The cubic root of 21052691 is about 276.1229717019.

The spelling of 21052691 in words is "twenty-one million, fifty-two thousand, six hundred ninety-one".