21221554 has 8 divisors (see below), whose sum is σ = 31852800. Its totient is φ = 10603956.

The previous prime is 21221539. The next prime is 21221561. The reversal of 21221554 is 45512212.

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

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 3 ways as a sum of consecutive naturals, for example, 2587 + ... + 7009.

It is an arithmetic number, because the mean of its divisors is an integer number (3981600).

Almost surely, 2^21221554 is an apocalyptic number.

21221554 is a deficient number, since it is larger than the sum of its proper divisors (10631246).

21221554 is a wasteful number, since it uses less digits than its factorization.

21221554 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6824.

The product of its digits is 800, while the sum is 22.

The square root of 21221554 is about 4606.6857934962. The cubic root of 21221554 is about 276.8592646137.

Adding to 21221554 its reverse (45512212), we get a palindrome (66733766).

The spelling of 21221554 in words is "twenty-one million, two hundred twenty-one thousand, five hundred fifty-four".