21093987 has 8 divisors (see below), whose sum is σ = 28160704. Its totient is φ = 14044968.

The previous prime is 21093913. The next prime is 21093997. The reversal of 21093987 is 78939012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21093987 - 2⁸ = 21093731 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21093907) 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 7 ways as a sum of consecutive naturals, for example, 1333 + ... + 6630.

It is an arithmetic number, because the mean of its divisors is an integer number (3520088).

Almost surely, 2^21093987 is an apocalyptic number.

21093987 is a deficient number, since it is larger than the sum of its proper divisors (7066717).

21093987 is an equidigital number, since it uses as much as digits as its factorization.

21093987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8849.

The product of its (nonzero) digits is 27216, while the sum is 39.

The square root of 21093987 is about 4592.8190689379. The cubic root of 21093987 is about 276.3033971977.

The spelling of 21093987 in words is "twenty-one million, ninety-three thousand, nine hundred eighty-seven".