1621995648 has 384 divisors, whose sum is σ = 5697720000. Its totient is φ = 404103168.

The previous prime is 1621995637. The next prime is 1621995691. The reversal of 1621995648 is 8465991261.

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

It is a self number, because there is not a number n which added to its sum of digits gives 1621995648.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 4647378 + ... + 4647726.

Almost surely, 2^1621995648 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1621995648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2848860000).

1621995648 is an abundant number, since it is smaller than the sum of its proper divisors (4075724352).

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

1621995648 is a wasteful number, since it uses less digits than its factorization.

1621995648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 412 (or 393 counting only the distinct ones).

The product of its digits is 933120, while the sum is 51.

The square root of 1621995648 is about 40274.0071013551. The cubic root of 1621995648 is about 1174.9423597498.

The spelling of 1621995648 in words is "one billion, six hundred twenty-one million, nine hundred ninety-five thousand, six hundred forty-eight".