1243991285 has 4 divisors (see below), whose sum is σ = 1492789548. Its totient is φ = 995193024.

The previous prime is 1243991257. The next prime is 1243991293. The reversal of 1243991285 is 5821993421.

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 749773924 + 494217361 = 27382^2 + 22231^2 .

It is a cyclic number.

It is not a de Polignac number, because 1243991285 - 2²⁴ = 1227214069 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 124399124 + ... + 124399133.

It is an arithmetic number, because the mean of its divisors is an integer number (373197387).

Almost surely, 2^1243991285 is an apocalyptic number.

It is an amenable number.

1243991285 is a deficient number, since it is larger than the sum of its proper divisors (248798263).

1243991285 is an equidigital number, since it uses as much as digits as its factorization.

1243991285 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 248798262.

The product of its digits is 155520, while the sum is 44.

The square root of 1243991285 is about 35270.2606313024. The cubic root of 1243991285 is about 1075.4885207079.

The spelling of 1243991285 in words is "one billion, two hundred forty-three million, nine hundred ninety-one thousand, two hundred eighty-five".