1621746644 has 24 divisors (see below), whose sum is σ = 3264981888. Its totient is φ = 690429600.

The previous prime is 1621746563. The next prime is 1621746647. The reversal of 1621746644 is 4466471261.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1621746647) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 187559 + ... + 196014.

It is an arithmetic number, because the mean of its divisors is an integer number (136040912).

Almost surely, 2^1621746644 is an apocalyptic number.

1621746644 is a gapful number since it is divisible by the number (14) formed by its first and last digit.

It is an amenable number.

1621746644 is an abundant number, since it is smaller than the sum of its proper divisors (1643235244).

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

1621746644 is a wasteful number, since it uses less digits than its factorization.

1621746644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 383735 (or 383733 counting only the distinct ones).

The product of its digits is 193536, while the sum is 41.

The square root of 1621746644 is about 40270.9156091589. The cubic root of 1621746644 is about 1174.8822321080.

The spelling of 1621746644 in words is "one billion, six hundred twenty-one million, seven hundred forty-six thousand, six hundred forty-four".