1231378281 has 45 divisors (see below), whose sum is σ = 2143635879. Its totient is φ = 702381456.

The previous prime is 1231378271. The next prime is 1231378283. The reversal of 1231378281 is 1828731321.

The square root of 1231378281 is 35091.

It is a perfect power (a square), and thus also a powerful number.

1231378281 is a `hidden beast` number, since 1 + 2 + 3 + 1 + 378 + 281 = 666.

It can be written as a sum of positive squares in only one way, i.e., 108056025 + 1123322256 = 10395^2 + 33516^2 .

It is not a de Polignac number, because 1231378281 - 2¹¹ = 1231376233 is a prime.

It is a super-2 number, since 2×1231378281² = 3032584941837029922, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1231378283) by changing a digit.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 2210455 + ... + 2211011.

Almost surely, 2^1231378281 is an apocalyptic number.

1231378281 is the 35091-st square number.

1231378281 is the 17546-th centered octagonal number.

It is an amenable number.

1231378281 is a deficient number, since it is larger than the sum of its proper divisors (912257598).

1231378281 is an frugal number, since it uses more digits than its factorization.

1231378281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1140 (or 567 counting only the distinct ones).

The product of its digits is 16128, while the sum is 36.

The cubic root of 1231378281 is about 1071.8413227792.

Multiplying 1231378281 by its sum of digits (36), we get a square (44329618116 = 210546²).

The spelling of 1231378281 in words is "one billion, two hundred thirty-one million, three hundred seventy-eight thousand, two hundred eighty-one".