1990864640 has 144 divisors (see below), whose sum is σ = 4973101056. Its totient is φ = 762777600.

The previous prime is 1990864627. The next prime is 1990864657. The reversal of 1990864640 is 464680991.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5197889 + ... + 5198271.

It is an arithmetic number, because the mean of its divisors is an integer number (34535424).

Almost surely, 2^1990864640 is an apocalyptic number.

1990864640 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 1990864640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2486550528).

1990864640 is an abundant number, since it is smaller than the sum of its proper divisors (2982236416).

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

1990864640 is a wasteful number, since it uses less digits than its factorization.

1990864640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 566 (or 552 counting only the distinct ones).

The product of its (nonzero) digits is 373248, while the sum is 47.

The square root of 1990864640 is about 44619.1062214384. The cubic root of 1990864640 is about 1257.9998163318. Note that the first 3 decimals are identical.

It can be divided in two parts, 19908 and 64640, that added together give a palindrome (84548).

The spelling of 1990864640 in words is "one billion, nine hundred ninety million, eight hundred sixty-four thousand, six hundred forty".