21087599 has 8 divisors (see below), whose sum is σ = 24045840. Its totient is φ = 18320256.

The previous prime is 21087593. The next prime is 21087607. The reversal of 21087599 is 99578012.

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

It is a cyclic number.

It is not a de Polignac number, because 21087599 - 2¹⁶ = 21022063 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21087593) 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, 47489 + ... + 47930.

It is an arithmetic number, because the mean of its divisors is an integer number (3005730).

Almost surely, 2^21087599 is an apocalyptic number.

21087599 is a deficient number, since it is larger than the sum of its proper divisors (2958241).

21087599 is a wasteful number, since it uses less digits than its factorization.

21087599 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95449.

The product of its (nonzero) digits is 45360, while the sum is 41.

The square root of 21087599 is about 4592.1235828318. The cubic root of 21087599 is about 276.2755029246.

The spelling of 21087599 in words is "twenty-one million, eighty-seven thousand, five hundred ninety-nine".