1997306640 has 480 divisors, whose sum is σ = 8121980160. Its totient is φ = 449777664.

The previous prime is 1997306639. The next prime is 1997306651. The reversal of 1997306640 is 466037991.

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

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 11959837 + ... + 11960003.

It is an arithmetic number, because the mean of its divisors is an integer number (16920792).

Almost surely, 2^1997306640 is an apocalyptic number.

1997306640 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 1997306640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4060990080).

1997306640 is an abundant number, since it is smaller than the sum of its proper divisors (6124673520).

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

1997306640 is a wasteful number, since it uses less digits than its factorization.

1997306640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 316 (or 297 counting only the distinct ones).

The product of its (nonzero) digits is 244944, while the sum is 45.

The square root of 1997306640 is about 44691.2367248882. The cubic root of 1997306640 is about 1259.3552256643.

The spelling of 1997306640 in words is "one billion, nine hundred ninety-seven million, three hundred six thousand, six hundred forty".