20859891 has 16 divisors (see below), whose sum is σ = 31530240. Its totient is φ = 12160800.

The previous prime is 20859889. The next prime is 20859893. The reversal of 20859891 is 19895802.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (20859889) and next prime (20859893).

It is not a de Polignac number, because 20859891 - 2¹ = 20859889 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20859893) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13335 + ... + 14816.

It is an arithmetic number, because the mean of its divisors is an integer number (1970640).

Almost surely, 2^20859891 is an apocalyptic number.

20859891 is a deficient number, since it is larger than the sum of its proper divisors (10670349).

20859891 is a wasteful number, since it uses less digits than its factorization.

20859891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28186.

The product of its (nonzero) digits is 51840, while the sum is 42.

The square root of 20859891 is about 4567.2629659348. The cubic root of 20859891 is about 275.2774764046.

The spelling of 20859891 in words is "twenty million, eight hundred fifty-nine thousand, eight hundred ninety-one".