1281639157 has 2 divisors, whose sum is σ = 1281639158. Its totient is φ = 1281639156.

The previous prime is 1281639127. The next prime is 1281639217. The reversal of 1281639157 is 7519361821.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1281568401 + 70756 = 35799^2 + 266^2 .

It is a cyclic number.

It is not a de Polignac number, because 1281639157 - 2¹¹ = 1281637109 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1281639127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 640819578 + 640819579.

It is an arithmetic number, because the mean of its divisors is an integer number (640819579).

Almost surely, 2^1281639157 is an apocalyptic number.

It is an amenable number.

1281639157 is a deficient number, since it is larger than the sum of its proper divisors (1).

1281639157 is an equidigital number, since it uses as much as digits as its factorization.

1281639157 is an evil number, because the sum of its binary digits is even.

The product of its digits is 90720, while the sum is 43.

The square root of 1281639157 is about 35799.9882262550. The cubic root of 1281639157 is about 1086.2303235877.

The spelling of 1281639157 in words is "one billion, two hundred eighty-one million, six hundred thirty-nine thousand, one hundred fifty-seven".