1638644730 has 64 divisors (see below), whose sum is σ = 3966693120. Its totient is φ = 433220096.

The previous prime is 1638644699. The next prime is 1638644737. The reversal of 1638644730 is 374468361.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (1638644737) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2509084 + ... + 2509736.

It is an arithmetic number, because the mean of its divisors is an integer number (61979580).

Almost surely, 2^1638644730 is an apocalyptic number.

1638644730 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1638644730 is an abundant number, since it is smaller than the sum of its proper divisors (2328048390).

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

1638644730 is a wasteful number, since it uses less digits than its factorization.

1638644730 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1255.

The product of its (nonzero) digits is 290304, while the sum is 42.

The square root of 1638644730 is about 40480.1770006012. The cubic root of 1638644730 is about 1178.9487741054.

It can be divided in two parts, 16386 and 44730, that added together give a palindrome (61116).

The spelling of 1638644730 in words is "one billion, six hundred thirty-eight million, six hundred forty-four thousand, seven hundred thirty".