20155815 has 12 divisors (see below), whose sum is σ = 34936824. Its totient is φ = 10749744.

The previous prime is 20155813. The next prime is 20155831. The reversal of 20155815 is 51855102.

20155815 is nontrivially palindromic in base 13.

It is not a de Polignac number, because 20155815 - 2¹ = 20155813 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20155813) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 223909 + ... + 223998.

It is an arithmetic number, because the mean of its divisors is an integer number (2911402).

Almost surely, 2^20155815 is an apocalyptic number.

20155815 is a deficient number, since it is larger than the sum of its proper divisors (14781009).

20155815 is a wasteful number, since it uses less digits than its factorization.

20155815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 447918 (or 447915 counting only the distinct ones).

The product of its (nonzero) digits is 2000, while the sum is 27.

The square root of 20155815 is about 4489.5228031496. The cubic root of 20155815 is about 272.1448505799.

The spelling of 20155815 in words is "twenty million, one hundred fifty-five thousand, eight hundred fifteen".