1321820640 has 192 divisors, whose sum is σ = 5287403520. Its totient is φ = 302123520.

The previous prime is 1321820623. The next prime is 1321820701. The reversal of 1321820640 is 460281231.

1321820640 is a `hidden beast` number, since 1 + 3 + 2 + 18 + 2 + 0 + 640 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 8385 + ... + 52095.

It is an arithmetic number, because the mean of its divisors is an integer number (27538560).

Almost surely, 2^1321820640 is an apocalyptic number.

1321820640 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 1321820640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2643701760).

1321820640 is an abundant number, since it is smaller than the sum of its proper divisors (3965582880).

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

1321820640 is a wasteful number, since it uses less digits than its factorization.

1321820640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43742 (or 43728 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 1321820640 is about 36356.8513488173. The cubic root of 1321820640 is about 1097.4654150644.

The spelling of 1321820640 in words is "one billion, three hundred twenty-one million, eight hundred twenty thousand, six hundred forty".