21281372 has 24 divisors (see below), whose sum is σ = 42856800. Its totient is φ = 9057600.

The previous prime is 21281369. The next prime is 21281441. The reversal of 21281372 is 27318212.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1622 + ... + 6722.

It is an arithmetic number, because the mean of its divisors is an integer number (1785700).

Almost surely, 2^21281372 is an apocalyptic number.

It is an amenable number.

21281372 is an abundant number, since it is smaller than the sum of its proper divisors (21575428).

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

21281372 is a wasteful number, since it uses less digits than its factorization.

21281372 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5261 (or 5259 counting only the distinct ones).

The product of its digits is 1344, while the sum is 26.

The square root of 21281372 is about 4613.1737448312. The cubic root of 21281372 is about 277.1191518221.

Adding to 21281372 its reverse (27318212), we get a palindrome (48599584).

The spelling of 21281372 in words is "twenty-one million, two hundred eighty-one thousand, three hundred seventy-two".