1643139421 has 8 divisors (see below), whose sum is σ = 2048589504. Its totient is φ = 1280368320.

The previous prime is 1643139413. The next prime is 1643139427. The reversal of 1643139421 is 1249313461.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1643139421 - 2³ = 1643139413 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 (1643139427) 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, 10669660 + ... + 10669813.

It is an arithmetic number, because the mean of its divisors is an integer number (256073688).

Almost surely, 2^1643139421 is an apocalyptic number.

1643139421 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1643139421 is a deficient number, since it is larger than the sum of its proper divisors (405450083).

1643139421 is a wasteful number, since it uses less digits than its factorization.

1643139421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21339491.

The product of its digits is 15552, while the sum is 34.

The square root of 1643139421 is about 40535.6561683661. The cubic root of 1643139421 is about 1180.0257154695.

The spelling of 1643139421 in words is "one billion, six hundred forty-three million, one hundred thirty-nine thousand, four hundred twenty-one".