21251472 has 60 divisors (see below), whose sum is σ = 60360720. Its totient is φ = 6438080.

The previous prime is 21251467. The next prime is 21251491. The reversal of 21251472 is 27415212.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3979 + ... + 7637.

It is an arithmetic number, because the mean of its divisors is an integer number (1006012).

Almost surely, 2^21251472 is an apocalyptic number.

21251472 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21251472, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30180360).

21251472 is an abundant number, since it is smaller than the sum of its proper divisors (39109248).

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

21251472 is a wasteful number, since it uses less digits than its factorization.

21251472 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3692 (or 3675 counting only the distinct ones).

The product of its digits is 1120, while the sum is 24.

The square root of 21251472 is about 4609.9318866985. The cubic root of 21251472 is about 276.9893082798.

Adding to 21251472 its reverse (27415212), we get a palindrome (48666684).

The spelling of 21251472 in words is "twenty-one million, two hundred fifty-one thousand, four hundred seventy-two".