1638807646 has 24 divisors (see below), whose sum is σ = 3010058280. Its totient is φ = 665379792.

The previous prime is 1638807631. The next prime is 1638807649. The reversal of 1638807646 is 6467088361.

It is a super-2 number, since 2×1638807646² = 5371381001176122632, which contains 22 as substring.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (49).

It is a self number, because there is not a number n which added to its sum of digits gives 1638807646.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1638807649) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 438205 + ... + 441928.

It is an arithmetic number, because the mean of its divisors is an integer number (125419095).

Almost surely, 2^1638807646 is an apocalyptic number.

1638807646 is a deficient number, since it is larger than the sum of its proper divisors (1371250634).

1638807646 is a wasteful number, since it uses less digits than its factorization.

1638807646 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 880168 (or 880161 counting only the distinct ones).

The product of its (nonzero) digits is 1161216, while the sum is 49.

The square root of 1638807646 is about 40482.1892441602. The cubic root of 1638807646 is about 1178.9878436385.

The spelling of 1638807646 in words is "one billion, six hundred thirty-eight million, eight hundred seven thousand, six hundred forty-six".