21986287 has 16 divisors (see below), whose sum is σ = 25090560. Its totient is φ = 19135872.

The previous prime is 21986273. The next prime is 21986309. The reversal of 21986287 is 78268912.

It is a cyclic number.

It is not a de Polignac number, because 21986287 - 2²³ = 13597679 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (43).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21986227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13098 + ... + 14680.

It is an arithmetic number, because the mean of its divisors is an integer number (1568160).

Almost surely, 2^21986287 is an apocalyptic number.

21986287 is a deficient number, since it is larger than the sum of its proper divisors (3104273).

21986287 is a wasteful number, since it uses less digits than its factorization.

21986287 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1662.

The product of its digits is 96768, while the sum is 43.

The square root of 21986287 is about 4688.9537212474. The cubic root of 21986287 is about 280.1457022297.

The spelling of 21986287 in words is "twenty-one million, nine hundred eighty-six thousand, two hundred eighty-seven".