421638389 has 4 divisors (see below), whose sum is σ = 422577900. Its totient is φ = 420698880.

The previous prime is 421638377. The next prime is 421638397. The reversal of 421638389 is 983836124.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 372876100 + 48762289 = 19310^2 + 6983^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-421638389 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (421638319) 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, 469082 + ... + 469979.

It is an arithmetic number, because the mean of its divisors is an integer number (105644475).

Almost surely, 2^421638389 is an apocalyptic number.

It is an amenable number.

421638389 is a deficient number, since it is larger than the sum of its proper divisors (939511).

421638389 is an equidigital number, since it uses as much as digits as its factorization.

421638389 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 939510.

The product of its digits is 248832, while the sum is 44.

The square root of 421638389 is about 20533.8352238446. The cubic root of 421638389 is about 749.8597598526.

The spelling of 421638389 in words is "four hundred twenty-one million, six hundred thirty-eight thousand, three hundred eighty-nine".