21942756 has 36 divisors (see below), whose sum is σ = 60509904. Its totient is φ = 6649200.

The previous prime is 21942751. The next prime is 21942757. The reversal of 21942756 is 65724912.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 21942756.

It is not an unprimeable number, because it can be changed into a prime (21942751) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 27310 + ... + 28101.

Almost surely, 2^21942756 is an apocalyptic number.

It is an amenable number.

21942756 is an abundant number, since it is smaller than the sum of its proper divisors (38567148).

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

21942756 is a wasteful number, since it uses less digits than its factorization.

21942756 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55432 (or 55427 counting only the distinct ones).

The product of its digits is 30240, while the sum is 36.

The square root of 21942756 is about 4684.3095542460. The cubic root of 21942756 is about 279.9606917608.

It can be divided in two parts, 2194 and 2756, that added together give a triangular number (4950 = T₉₉).

The spelling of 21942756 in words is "twenty-one million, nine hundred forty-two thousand, seven hundred fifty-six".