21799087 has 4 divisors (see below), whose sum is σ = 21810256. Its totient is φ = 21787920.

The previous prime is 21799079. The next prime is 21799091. The reversal of 21799087 is 78099712.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21799087 - 2³ = 21799079 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 (21799487) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1803 + ... + 6844.

It is an arithmetic number, because the mean of its divisors is an integer number (5452564).

Almost surely, 2^21799087 is an apocalyptic number.

21799087 is a deficient number, since it is larger than the sum of its proper divisors (11169).

21799087 is an equidigital number, since it uses as much as digits as its factorization.

21799087 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11168.

The product of its (nonzero) digits is 63504, while the sum is 43.

The square root of 21799087 is about 4668.9492393900. The cubic root of 21799087 is about 279.3483442446.

The spelling of 21799087 in words is "twenty-one million, seven hundred ninety-nine thousand, eighty-seven".