21551456 has 24 divisors (see below), whose sum is σ = 42565320. Its totient is φ = 10741248.

The previous prime is 21551449. The next prime is 21551459. The reversal of 21551456 is 65415512.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21551459) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11240 + ... + 13016.

It is an arithmetic number, because the mean of its divisors is an integer number (1773555).

Almost surely, 2^21551456 is an apocalyptic number.

It is an amenable number.

21551456 is a deficient number, since it is larger than the sum of its proper divisors (21013864).

21551456 is a wasteful number, since it uses less digits than its factorization.

21551456 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2166 (or 2158 counting only the distinct ones).

The product of its digits is 6000, while the sum is 29.

The square root of 21551456 is about 4642.3545749975. The cubic root of 21551456 is about 278.2865427060.

Adding to 21551456 its reverse (65415512), we get a palindrome (86966968).

The spelling of 21551456 in words is "twenty-one million, five hundred fifty-one thousand, four hundred fifty-six".