21809952 has 48 divisors (see below), whose sum is σ = 63614880. Its totient is φ = 7269696.

The previous prime is 21809951. The next prime is 21809971. The reversal of 21809952 is 25990812.

It is a tau number, because it is divible by the number of its divisors (48).

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

It is not an unprimeable number, because it can be changed into a prime (21809951) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11758 + ... + 13485.

It is an arithmetic number, because the mean of its divisors is an integer number (1325310).

Almost surely, 2^21809952 is an apocalyptic number.

It is an amenable number.

21809952 is an abundant number, since it is smaller than the sum of its proper divisors (41804928).

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

21809952 is a wasteful number, since it uses less digits than its factorization.

21809952 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25262 (or 25248 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 36.

The square root of 21809952 is about 4670.1126324747. The cubic root of 21809952 is about 279.3947470389.

The spelling of 21809952 in words is "twenty-one million, eight hundred nine thousand, nine hundred fifty-two".