1239643381 has 4 divisors (see below), whose sum is σ = 1240377292. Its totient is φ = 1238909472.

The previous prime is 1239643369. The next prime is 1239643387. The reversal of 1239643381 is 1833469321.

It is a happy number.

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 823116100 + 416527281 = 28690^2 + 20409^2 .

It is a cyclic number.

It is not a de Polignac number, because 1239643381 - 2⁷ = 1239643253 is a prime.

It is a super-2 number, since 2×1239643381² = 3073431424114222322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1239643387) 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, 364416 + ... + 367801.

It is an arithmetic number, because the mean of its divisors is an integer number (310094323).

Almost surely, 2^1239643381 is an apocalyptic number.

It is an amenable number.

1239643381 is a deficient number, since it is larger than the sum of its proper divisors (733911).

1239643381 is an equidigital number, since it uses as much as digits as its factorization.

1239643381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 733910.

The product of its digits is 93312, while the sum is 40.

The square root of 1239643381 is about 35208.5697096602. The cubic root of 1239643381 is about 1074.2340694442.

The spelling of 1239643381 in words is "one billion, two hundred thirty-nine million, six hundred forty-three thousand, three hundred eighty-one".