1639381 has 2 divisors, whose sum is σ = 1639382. Its totient is φ = 1639380.

The previous prime is 1639367. The next prime is 1639387. The reversal of 1639381 is 1839361.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1418481 + 220900 = 1191^2 + 470^2 .

It is an emirp because it is prime and its reverse (1839361) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1639381 - 2⁵ = 1639349 is a prime.

It is a super-2 number, since 2×1639381² = 5375140126322, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1639387) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 819690 + 819691.

It is an arithmetic number, because the mean of its divisors is an integer number (819691).

2^1639381 is an apocalyptic number.

It is an amenable number.

1639381 is a deficient number, since it is larger than the sum of its proper divisors (1).

1639381 is an equidigital number, since it uses as much as digits as its factorization.

1639381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3888, while the sum is 31.

The square root of 1639381 is about 1280.3831457810. The cubic root of 1639381 is about 117.9125321351.

The spelling of 1639381 in words is "one million, six hundred thirty-nine thousand, three hundred eighty-one".