20993287 has 4 divisors (see below), whose sum is σ = 23992336. Its totient is φ = 17994240.

The previous prime is 20993281. The next prime is 20993339. The reversal of 20993287 is 78239902.

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 20993287 - 2³ = 20993279 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 (20993281) 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, 1499514 + ... + 1499527.

It is an arithmetic number, because the mean of its divisors is an integer number (5998084).

Almost surely, 2^20993287 is an apocalyptic number.

20993287 is a deficient number, since it is larger than the sum of its proper divisors (2999049).

20993287 is an equidigital number, since it uses as much as digits as its factorization.

20993287 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2999048.

The product of its (nonzero) digits is 54432, while the sum is 40.

The square root of 20993287 is about 4581.8431880631. The cubic root of 20993287 is about 275.8630166352.

The spelling of 20993287 in words is "twenty million, nine hundred ninety-three thousand, two hundred eighty-seven".