21372554 has 8 divisors (see below), whose sum is σ = 36638688. Its totient is φ = 9159660.

The previous prime is 21372551. The next prime is 21372563. The reversal of 21372554 is 45527312.

It is a happy number.

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

It is not an unprimeable number, because it can be changed into a prime (21372551) 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 3 ways as a sum of consecutive naturals, for example, 763292 + ... + 763319.

It is an arithmetic number, because the mean of its divisors is an integer number (4579836).

Almost surely, 2^21372554 is an apocalyptic number.

21372554 is a deficient number, since it is larger than the sum of its proper divisors (15266134).

21372554 is a wasteful number, since it uses less digits than its factorization.

21372554 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1526620.

The product of its digits is 8400, while the sum is 29.

The square root of 21372554 is about 4623.0459655945. The cubic root of 21372554 is about 277.5143687606.

Adding to 21372554 its reverse (45527312), we get a palindrome (66899866).

The spelling of 21372554 in words is "twenty-one million, three hundred seventy-two thousand, five hundred fifty-four".