21809554 has 16 divisors (see below), whose sum is σ = 36368640. Its totient is φ = 9740880.

The previous prime is 21809533. The next prime is 21809561. The reversal of 21809554 is 45590812.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 12724 + ... + 14335.

It is an arithmetic number, because the mean of its divisors is an integer number (2273040).

Almost surely, 2^21809554 is an apocalyptic number.

21809554 is a deficient number, since it is larger than the sum of its proper divisors (14559086).

21809554 is a wasteful number, since it uses less digits than its factorization.

21809554 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27105.

The product of its (nonzero) digits is 14400, while the sum is 34.

The square root of 21809554 is about 4670.0700208883. The cubic root of 21809554 is about 279.3930475123.

The spelling of 21809554 in words is "twenty-one million, eight hundred nine thousand, five hundred fifty-four".