1581215947 has 2 divisors, whose sum is σ = 1581215948. Its totient is φ = 1581215946.

The previous prime is 1581215921. The next prime is 1581216001. The reversal of 1581215947 is 7495121851.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1581215947 is a prime.

It is not a weakly prime, because it can be changed into another prime (1581213947) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 790607973 + 790607974.

It is an arithmetic number, because the mean of its divisors is an integer number (790607974).

Almost surely, 2^1581215947 is an apocalyptic number.

1581215947 is a deficient number, since it is larger than the sum of its proper divisors (1).

1581215947 is an equidigital number, since it uses as much as digits as its factorization.

1581215947 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 100800, while the sum is 43.

The square root of 1581215947 is about 39764.5061204084. The cubic root of 1581215947 is about 1165.0119905193.

The spelling of 1581215947 in words is "one billion, five hundred eighty-one million, two hundred fifteen thousand, nine hundred forty-seven".