1990638720 has 384 divisors, whose sum is σ = 8204716800. Its totient is φ = 454809600.

The previous prime is 1990638691. The next prime is 1990638731. The reversal of 1990638720 is 278360991.

1990638720 is a `hidden beast` number, since 1 + 9 + 9 + 0 + 638 + 7 + 2 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (384).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 845545 + ... + 847895.

It is an arithmetic number, because the mean of its divisors is an integer number (21366450).

Almost surely, 2^1990638720 is an apocalyptic number.

1990638720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1990638720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4102358400).

1990638720 is an abundant number, since it is smaller than the sum of its proper divisors (6214078080).

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

1990638720 is a wasteful number, since it uses less digits than its factorization.

1990638720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2393 (or 2368 counting only the distinct ones).

The product of its (nonzero) digits is 163296, while the sum is 45.

The square root of 1990638720 is about 44616.5744987219. The cubic root of 1990638720 is about 1257.9522292911.

The spelling of 1990638720 in words is "one billion, nine hundred ninety million, six hundred thirty-eight thousand, seven hundred twenty".