21274624 has 84 divisors (see below), whose sum is σ = 50426874. Its totient is φ = 8945664.

The previous prime is 21274619. The next prime is 21274639. The reversal of 21274624 is 42647212.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 16257024 + 5017600 = 4032^2 + 2240^2 .

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a junction number, because it is equal to n+sod(n) for n = 21274592 and 21274601.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 401382 + ... + 401434.

Almost surely, 2^21274624 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21274624, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25213437).

21274624 is an abundant number, since it is smaller than the sum of its proper divisors (29152250).

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

21274624 is an frugal number, since it uses more digits than its factorization.

21274624 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 93 (or 62 counting only the distinct ones).

The product of its digits is 5376, while the sum is 28.

The square root of 21274624 is about 4612.4423031622. The cubic root of 21274624 is about 277.0898586336.

The spelling of 21274624 in words is "twenty-one million, two hundred seventy-four thousand, six hundred twenty-four".