20115864 has 80 divisors (see below), whose sum is σ = 57934800. Its totient is φ = 6516288.

The previous prime is 20115853. The next prime is 20115883. The reversal of 20115864 is 46851102.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 23557 + ... + 24395.

It is an arithmetic number, because the mean of its divisors is an integer number (724185).

Almost surely, 2^20115864 is an apocalyptic number.

20115864 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20115864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28967400).

20115864 is an abundant number, since it is smaller than the sum of its proper divisors (37818936).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20115864 is a wasteful number, since it uses less digits than its factorization.

20115864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 894 (or 881 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 20115864 is about 4485.0712368925. The cubic root of 20115864 is about 271.9649248312.

Adding to 20115864 its reverse (46851102), we get a palindrome (66966966).

It can be divided in two parts, 2011 and 5864, that added together give a triangular number (7875 = T₁₂₅).

The spelling of 20115864 in words is "twenty million, one hundred fifteen thousand, eight hundred sixty-four".