1638064387 has 4 divisors (see below), whose sum is σ = 1638755896. Its totient is φ = 1637372880.

The previous prime is 1638064369. The next prime is 1638064409. The reversal of 1638064387 is 7834608361.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7834608361 = 29 ⋅270158909.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1638064387 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1638064357) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 342189 + ... + 346942.

It is an arithmetic number, because the mean of its divisors is an integer number (409688974).

Almost surely, 2^1638064387 is an apocalyptic number.

1638064387 is a deficient number, since it is larger than the sum of its proper divisors (691509).

1638064387 is an equidigital number, since it uses as much as digits as its factorization.

1638064387 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 691508.

The product of its (nonzero) digits is 580608, while the sum is 46.

The square root of 1638064387 is about 40473.0081288752. The cubic root of 1638064387 is about 1178.8095786993.

The spelling of 1638064387 in words is "one billion, six hundred thirty-eight million, sixty-four thousand, three hundred eighty-seven".