21827987 has 4 divisors (see below), whose sum is σ = 21843360. Its totient is φ = 21812616.

The previous prime is 21827977. The next prime is 21828029. The reversal of 21827987 is 78972812.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21827987 - 2¹² = 21823891 is a prime.

It is a super-2 number, since 2×21827987² = 952922032944338, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21827917) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 5312 + ... + 8477.

It is an arithmetic number, because the mean of its divisors is an integer number (5460840).

Almost surely, 2^21827987 is an apocalyptic number.

21827987 is a deficient number, since it is larger than the sum of its proper divisors (15373).

21827987 is a wasteful number, since it uses less digits than its factorization.

21827987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15372.

The product of its digits is 112896, while the sum is 44.

The square root of 21827987 is about 4672.0431290818. The cubic root of 21827987 is about 279.4717378241.

The spelling of 21827987 in words is "twenty-one million, eight hundred twenty-seven thousand, nine hundred eighty-seven".