21427553 has 16 divisors (see below), whose sum is σ = 25200000. Its totient is φ = 18211536.

The previous prime is 21427537. The next prime is 21427583. The reversal of 21427553 is 35572412.

It is a happy number.

It is not a de Polignac number, because 21427553 - 2⁴ = 21427537 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21427583) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 61223 + ... + 61571.

It is an arithmetic number, because the mean of its divisors is an integer number (1575000).

Almost surely, 2^21427553 is an apocalyptic number.

It is an amenable number.

21427553 is a deficient number, since it is larger than the sum of its proper divisors (3772447).

21427553 is an equidigital number, since it uses as much as digits as its factorization.

21427553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 549 (or 535 counting only the distinct ones).

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

The square root of 21427553 is about 4628.9904946975. The cubic root of 21427553 is about 277.7522117922.

Adding to 21427553 its reverse (35572412), we get a palindrome (56999965).

The spelling of 21427553 in words is "twenty-one million, four hundred twenty-seven thousand, five hundred fifty-three".