2165000400 has 150 divisors (see below), whose sum is σ = 7770128982. Its totient is φ = 577324800.

The previous prime is 2165000399. The next prime is 2165000459. The reversal of 2165000400 is 40005612.

It is a happy number.

2165000400 is a `hidden beast` number, since 216 + 50 + 0 + 0 + 400 = 666.

It can be written as a sum of positive squares in 3 ways, for example, as 4981824 + 2160018576 = 2232^2 + 46476^2 .

It is a tau number, because it is divible by the number of its divisors (150).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 1011 + ... + 65810.

Almost surely, 2^2165000400 is an apocalyptic number.

2165000400 is a gapful number since it is divisible by the number (20) 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 2165000400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3885064491).

2165000400 is an abundant number, since it is smaller than the sum of its proper divisors (5605128582).

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

2165000400 is a wasteful number, since it uses less digits than its factorization.

2165000400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66851 (or 66831 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 2165000400 is about 46529.5647948699. The cubic root of 2165000400 is about 1293.6575485290.

The spelling of 2165000400 in words is "two billion, one hundred sixty-five million, four hundred", and thus it is an aban number.