21756522 has 8 divisors (see below), whose sum is σ = 43513056. Its totient is φ = 7252172.

The previous prime is 21756517. The next prime is 21756529. The reversal of 21756522 is 22565712.

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

21756522 is an admirable number.

It is a self number, because there is not a number n which added to its sum of digits gives 21756522.

It is not an unprimeable number, because it can be changed into a prime (21756529) 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, 1813038 + ... + 1813049.

It is an arithmetic number, because the mean of its divisors is an integer number (5439132).

Almost surely, 2^21756522 is an apocalyptic number.

21756522 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21756522 is a wasteful number, since it uses less digits than its factorization.

21756522 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3626092.

The product of its digits is 8400, while the sum is 30.

The square root of 21756522 is about 4664.3887059292. The cubic root of 21756522 is about 279.1664068115.

The spelling of 21756522 in words is "twenty-one million, seven hundred fifty-six thousand, five hundred twenty-two".