1291840427 has 2 divisors, whose sum is σ = 1291840428. Its totient is φ = 1291840426.

The previous prime is 1291840411. The next prime is 1291840439. The reversal of 1291840427 is 7240481921.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1291840427 - 2⁴ = 1291840411 is a prime.

It is not a weakly prime, because it can be changed into another prime (1291840447) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 645920213 + 645920214.

It is an arithmetic number, because the mean of its divisors is an integer number (645920214).

Almost surely, 2^1291840427 is an apocalyptic number.

1291840427 is a deficient number, since it is larger than the sum of its proper divisors (1).

1291840427 is an equidigital number, since it uses as much as digits as its factorization.

1291840427 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32256, while the sum is 38.

The square root of 1291840427 is about 35942.1817228726. The cubic root of 1291840427 is about 1089.1046787547.

The spelling of 1291840427 in words is "one billion, two hundred ninety-one million, eight hundred forty thousand, four hundred twenty-seven".