20993851 has 8 divisors (see below), whose sum is σ = 21970304. Its totient is φ = 20036160.

The previous prime is 20993839. The next prime is 20993857. The reversal of 20993851 is 15839902.

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 20993851 - 2⁹ = 20993339 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20993851.

It is not an unprimeable number, because it can be changed into a prime (20993857) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2376 + ... + 6901.

It is an arithmetic number, because the mean of its divisors is an integer number (2746288).

Almost surely, 2^20993851 is an apocalyptic number.

20993851 is a deficient number, since it is larger than the sum of its proper divisors (976453).

20993851 is an equidigital number, since it uses as much as digits as its factorization.

20993851 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9381.

The product of its (nonzero) digits is 19440, while the sum is 37.

The square root of 20993851 is about 4581.9047349328. The cubic root of 20993851 is about 275.8654870336.

The spelling of 20993851 in words is "twenty million, nine hundred ninety-three thousand, eight hundred fifty-one".