1865409640 has 24 divisors (see below), whose sum is σ = 4197786390. Its totient is φ = 746054592.

The previous prime is 1865409631. The next prime is 1865409647. The reversal of 1865409640 is 469045681.

It can be written as a sum of positive squares in 3 ways, for example, as 1553463396 + 311946244 = 39414^2 + 17662^2 .

It is not an unprimeable number, because it can be changed into a prime (1865409647) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 269746 + ... + 276574.

Almost surely, 2^1865409640 is an apocalyptic number.

1865409640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1865409640 is an abundant number, since it is smaller than the sum of its proper divisors (2332376750).

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

1865409640 is an frugal number, since it uses more digits than its factorization.

1865409640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13669 (or 6836 counting only the distinct ones).

The product of its (nonzero) digits is 207360, while the sum is 43.

The square root of 1865409640 is about 43190.3882825797. The cubic root of 1865409640 is about 1231.0000547724. Note that the first 4 decimals are identical.

Multiplying 1865409640 by its product of nonzero digits (207360), we get a square (386811342950400 = 19667520²).

The spelling of 1865409640 in words is "one billion, eight hundred sixty-five million, four hundred nine thousand, six hundred forty".