21056269 has 4 divisors (see below), whose sum is σ = 22675996. Its totient is φ = 19436544.

The previous prime is 21056263. The next prime is 21056281. The reversal of 21056269 is 96265012.

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 1075369 + 19980900 = 1037^2 + 4470^2 .

It is a cyclic number.

It is not a de Polignac number, because 21056269 - 2¹⁵ = 21023501 is a prime.

It is a super-3 number, since 3×21056269³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

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 21056269.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21056263) 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, 809844 + ... + 809869.

It is an arithmetic number, because the mean of its divisors is an integer number (5668999).

Almost surely, 2^21056269 is an apocalyptic number.

It is an amenable number.

21056269 is a deficient number, since it is larger than the sum of its proper divisors (1619727).

21056269 is a wasteful number, since it uses less digits than its factorization.

21056269 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1619726.

The product of its (nonzero) digits is 6480, while the sum is 31.

The square root of 21056269 is about 4588.7110390610. The cubic root of 21056269 is about 276.1386135982.

The spelling of 21056269 in words is "twenty-one million, fifty-six thousand, two hundred sixty-nine".