21278299 has 12 divisors (see below), whose sum is σ = 24874344. Its totient is φ = 18148704.

The previous prime is 21278297. The next prime is 21278311. The reversal of 21278299 is 99287212.

It is not a de Polignac number, because 21278299 - 2¹ = 21278297 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21278297) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10167 + ... + 12079.

It is an arithmetic number, because the mean of its divisors is an integer number (2072862).

Almost surely, 2^21278299 is an apocalyptic number.

21278299 is a deficient number, since it is larger than the sum of its proper divisors (3596045).

21278299 is a wasteful number, since it uses less digits than its factorization.

21278299 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2154 (or 2147 counting only the distinct ones).

The product of its digits is 36288, while the sum is 40.

The square root of 21278299 is about 4612.8406649265. The cubic root of 21278299 is about 277.1058126422.

The spelling of 21278299 in words is "twenty-one million, two hundred seventy-eight thousand, two hundred ninety-nine".