3865155840 has 576 divisors, whose sum is σ = 16894886400. Its totient is φ = 814841856.

The previous prime is 3865155781. The next prime is 3865155851. The reversal of 3865155840 is 485515683.

3865155840 is a `hidden beast` number, since 3 + 8 + 6 + 51 + 558 + 40 = 666.

It is a tau number, because it is divible by the number of its divisors (576).

It is a super-2 number, since 2×3865155840² = 29878859334972211200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3144346 + ... + 3145574.

It is an arithmetic number, because the mean of its divisors is an integer number (29331400).

Almost surely, 2^3865155840 is an apocalyptic number.

3865155840 is a gapful number since it is divisible by the number (30) 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 3865155840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (8447443200).

3865155840 is an abundant number, since it is smaller than the sum of its proper divisors (13029730560).

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

3865155840 is a wasteful number, since it uses less digits than its factorization.

3865155840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1279 (or 1259 counting only the distinct ones).

The product of its (nonzero) digits is 576000, while the sum is 45.

The square root of 3865155840 is about 62170.3775121239. The cubic root of 3865155840 is about 1569.3591228522.

The spelling of 3865155840 in words is "three billion, eight hundred sixty-five million, one hundred fifty-five thousand, eight hundred forty".