21242574 has 48 divisors (see below), whose sum is σ = 48288240. Its totient is φ = 6998400.

The previous prime is 21242569. The next prime is 21242591. The reversal of 21242574 is 47524212.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 52774 + ... + 53174.

It is an arithmetic number, because the mean of its divisors is an integer number (1006005).

Almost surely, 2^21242574 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21242574, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24144120).

21242574 is an abundant number, since it is smaller than the sum of its proper divisors (27045666).

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

21242574 is a wasteful number, since it uses less digits than its factorization.

21242574 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 527 (or 515 counting only the distinct ones).

The product of its digits is 4480, while the sum is 27.

The square root of 21242574 is about 4608.9666954752. The cubic root of 21242574 is about 276.9506443710.

Adding to 21242574 its reverse (47524212), we get a palindrome (68766786).

The spelling of 21242574 in words is "twenty-one million, two hundred forty-two thousand, five hundred seventy-four".