21391248 has 40 divisors (see below), whose sum is σ = 55427008. Its totient is φ = 7108992.

The previous prime is 21391213. The next prime is 21391259. The reversal of 21391248 is 84219312.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 29061 + ... + 29787.

Almost surely, 2^21391248 is an apocalyptic number.

It is an amenable number.

21391248 is an abundant number, since it is smaller than the sum of its proper divisors (34035760).

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

21391248 is a wasteful number, since it uses less digits than its factorization.

21391248 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1351 (or 1345 counting only the distinct ones).

The product of its digits is 3456, while the sum is 30.

The square root of 21391248 is about 4625.0673508610. The cubic root of 21391248 is about 277.5952566412.

The spelling of 21391248 in words is "twenty-one million, three hundred ninety-one thousand, two hundred forty-eight".