1638267421 has 12 divisors (see below), whose sum is σ = 1911068640. Its totient is φ = 1400302680.

The previous prime is 1638267377. The next prime is 1638267431. The reversal of 1638267421 is 1247628361.

It is not a de Polignac number, because 1638267421 - 2⁹ = 1638266909 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 (1638267431) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 28975 + ... + 64156.

It is an arithmetic number, because the mean of its divisors is an integer number (159255720).

Almost surely, 2^1638267421 is an apocalyptic number.

It is an amenable number.

1638267421 is a deficient number, since it is larger than the sum of its proper divisors (272801219).

1638267421 is an equidigital number, since it uses as much as digits as its factorization.

1638267421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 93504 (or 93497 counting only the distinct ones).

The product of its digits is 96768, while the sum is 40.

The square root of 1638267421 is about 40475.5163154221. The cubic root of 1638267421 is about 1178.8582801908.

The spelling of 1638267421 in words is "one billion, six hundred thirty-eight million, two hundred sixty-seven thousand, four hundred twenty-one".