21069756 has 18 divisors (see below), whose sum is σ = 53259752. Its totient is φ = 7023240.

The previous prime is 21069751. The next prime is 21069757. The reversal of 21069756 is 65796012.

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 585271 = 21069756 / (2 + 1 + 0 + 6 + 9 + 7 + 5 + 6).

It is a self number, because there is not a number n which added to its sum of digits gives 21069756.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21069751) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 292600 + ... + 292671.

Almost surely, 2^21069756 is an apocalyptic number.

It is an amenable number.

21069756 is an abundant number, since it is smaller than the sum of its proper divisors (32189996).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21069756 is a wasteful number, since it uses less digits than its factorization.

21069756 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 585281 (or 585276 counting only the distinct ones).

The product of its (nonzero) digits is 22680, while the sum is 36.

The square root of 21069756 is about 4590.1803886122. The cubic root of 21069756 is about 276.1975586184.

The spelling of 21069756 in words is "twenty-one million, sixty-nine thousand, seven hundred fifty-six".