1638994380 has 24 divisors (see below), whose sum is σ = 4589184432. Its totient is φ = 437065152.

The previous prime is 1638994369. The next prime is 1638994411. The reversal of 1638994380 is 834998361.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13658227 + ... + 13658346.

It is an arithmetic number, because the mean of its divisors is an integer number (191216018).

Almost surely, 2^1638994380 is an apocalyptic number.

1638994380 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1638994380 is an abundant number, since it is smaller than the sum of its proper divisors (2950190052).

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

1638994380 is a wasteful number, since it uses less digits than its factorization.

1638994380 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27316585 (or 27316583 counting only the distinct ones).

The product of its (nonzero) digits is 1119744, while the sum is 51.

The square root of 1638994380 is about 40484.4955507661. The cubic root of 1638994380 is about 1179.0326218761.

The spelling of 1638994380 in words is "one billion, six hundred thirty-eight million, nine hundred ninety-four thousand, three hundred eighty".