21551454 has 16 divisors (see below), whose sum is σ = 47892240. Its totient is φ = 7183800.

The previous prime is 21551449. The next prime is 21551459. The reversal of 21551454 is 45415512.

It is an interprime number because it is at equal distance from previous prime (21551449) and next prime (21551459).

It is a Harshad number since it is a multiple of its sum of digits (27).

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

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 199497 + ... + 199604.

It is an arithmetic number, because the mean of its divisors is an integer number (2993265).

Almost surely, 2^21551454 is an apocalyptic number.

21551454 is an abundant number, since it is smaller than the sum of its proper divisors (26340786).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21551454 is a wasteful number, since it uses less digits than its factorization.

21551454 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 399112 (or 399106 counting only the distinct ones).

The product of its digits is 4000, while the sum is 27.

The square root of 21551454 is about 4642.3543595895. The cubic root of 21551454 is about 278.2865340975.

Adding to 21551454 its reverse (45415512), we get a palindrome (66966966).

The spelling of 21551454 in words is "twenty-one million, five hundred fifty-one thousand, four hundred fifty-four".