21909550 has 48 divisors (see below), whose sum is σ = 45122112. Its totient is φ = 7862400.

The previous prime is 21909541. The next prime is 21909557. The reversal of 21909550 is 5590912.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21909557) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 23595 + ... + 24505.

It is an arithmetic number, because the mean of its divisors is an integer number (940044).

Almost surely, 2^21909550 is an apocalyptic number.

21909550 is an abundant number, since it is smaller than the sum of its proper divisors (23212562).

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

21909550 is a wasteful number, since it uses less digits than its factorization.

21909550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 973 (or 968 counting only the distinct ones).

The product of its (nonzero) digits is 4050, while the sum is 31.

The square root of 21909550 is about 4680.7638265565. The cubic root of 21909550 is about 279.8193988427.

The spelling of 21909550 in words is "twenty-one million, nine hundred nine thousand, five hundred fifty".