21799287 has 28 divisors (see below), whose sum is σ = 34626240. Its totient is φ = 13670208.

The previous prime is 21799279. The next prime is 21799301. The reversal of 21799287 is 78299712.

It is not a de Polignac number, because 21799287 - 2³ = 21799279 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21799487) 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 27 ways as a sum of consecutive naturals, for example, 11514 + ... + 13272.

Almost surely, 2^21799287 is an apocalyptic number.

21799287 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

21799287 is a deficient number, since it is larger than the sum of its proper divisors (12826953).

21799287 is an equidigital number, since it uses as much as digits as its factorization.

21799287 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1794 (or 1779 counting only the distinct ones).

The product of its digits is 127008, while the sum is 45.

The square root of 21799287 is about 4668.9706574362. The cubic root of 21799287 is about 279.3491985541.

The spelling of 21799287 in words is "twenty-one million, seven hundred ninety-nine thousand, two hundred eighty-seven".