1621220640 has 576 divisors, whose sum is σ = 6238632960. Its totient is φ = 350945280.

The previous prime is 1621220639. The next prime is 1621220677. The reversal of 1621220640 is 460221261.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 1621220640.

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, 52297425 + ... + 52297455.

It is an arithmetic number, because the mean of its divisors is an integer number (10830960).

Almost surely, 2^1621220640 is an apocalyptic number.

1621220640 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 1621220640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3119316480).

1621220640 is an abundant number, since it is smaller than the sum of its proper divisors (4617412320).

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

1621220640 is a wasteful number, since it uses less digits than its factorization.

1621220640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 125 (or 100 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 24.

The square root of 1621220640 is about 40264.3842620249. The cubic root of 1621220640 is about 1174.7551963218.

The spelling of 1621220640 in words is "one billion, six hundred twenty-one million, two hundred twenty thousand, six hundred forty".