20151851 has 4 divisors (see below), whose sum is σ = 21337272. Its totient is φ = 18966432.

The previous prime is 20151827. The next prime is 20151871. The reversal of 20151851 is 15815102.

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 20151851 - 2²² = 15957547 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20151871) 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, 592685 + ... + 592718.

It is an arithmetic number, because the mean of its divisors is an integer number (5334318).

Almost surely, 2^20151851 is an apocalyptic number.

20151851 is a deficient number, since it is larger than the sum of its proper divisors (1185421).

20151851 is a wasteful number, since it uses less digits than its factorization.

20151851 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1185420.

The product of its (nonzero) digits is 400, while the sum is 23.

The square root of 20151851 is about 4489.0813091322. The cubic root of 20151851 is about 272.1270086996.

Adding to 20151851 its reverse (15815102), we get a palindrome (35966953).

The spelling of 20151851 in words is "twenty million, one hundred fifty-one thousand, eight hundred fifty-one".