1621563622656 has 144 divisors (see below), whose sum is σ = 4546053368640. Its totient is φ = 511713607680.

The previous prime is 1621563622607. The next prime is 1621563622687. The reversal of 1621563622656 is 6562263651261.

It is a junction number, because it is equal to n+sod(n) for n = 1621563622599 and 1621563622608.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21163936 + ... + 21240416.

It is an arithmetic number, because the mean of its divisors is an integer number (31569815060).

Almost surely, 2^{1621563622656} is an apocalyptic number.

1621563622656 is a gapful number since it is divisible by the number (16) 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 1621563622656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2273026684320).

1621563622656 is an abundant number, since it is smaller than the sum of its proper divisors (2924489745984).

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

1621563622656 is a wasteful number, since it uses less digits than its factorization.

1621563622656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77972 (or 77958 counting only the distinct ones).

The product of its digits is 4665600, while the sum is 51.

The spelling of 1621563622656 in words is "one trillion, six hundred twenty-one billion, five hundred sixty-three million, six hundred twenty-two thousand, six hundred fifty-six".