1621944309 has 4 divisors (see below), whose sum is σ = 2162592416. Its totient is φ = 1081296204.

The previous prime is 1621944301. The next prime is 1621944323. The reversal of 1621944309 is 9034491261.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 1621944309 - 2³ = 1621944301 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1621944301) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 270324049 + ... + 270324054.

It is an arithmetic number, because the mean of its divisors is an integer number (540648104).

Almost surely, 2^1621944309 is an apocalyptic number.

It is an amenable number.

1621944309 is a deficient number, since it is larger than the sum of its proper divisors (540648107).

1621944309 is an equidigital number, since it uses as much as digits as its factorization.

1621944309 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 540648106.

The product of its (nonzero) digits is 46656, while the sum is 39.

The square root of 1621944309 is about 40273.3697249187. The cubic root of 1621944309 is about 1174.9299632919.

The spelling of 1621944309 in words is "one billion, six hundred twenty-one million, nine hundred forty-four thousand, three hundred nine".