1581216001 has 2 divisors, whose sum is σ = 1581216002. Its totient is φ = 1581216000.

The previous prime is 1581215947. The next prime is 1581216017. The reversal of 1581216001 is 1006121851.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1376039025 + 205176976 = 37095^2 + 14324^2 .

It is a cyclic number.

It is not a de Polignac number, because 1581216001 - 2⁷ = 1581215873 is a prime.

It is not a weakly prime, because it can be changed into another prime (1581216031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 790608000 + 790608001.

It is an arithmetic number, because the mean of its divisors is an integer number (790608001).

Almost surely, 2^1581216001 is an apocalyptic number.

It is an amenable number.

1581216001 is a deficient number, since it is larger than the sum of its proper divisors (1).

1581216001 is an equidigital number, since it uses as much as digits as its factorization.

1581216001 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 480, while the sum is 25.

The square root of 1581216001 is about 39764.5067994059. The cubic root of 1581216001 is about 1165.0120037813.

Adding to 1581216001 its reverse (1006121851), we get a palindrome (2587337852).

It can be divided in two parts, 15812 and 16001, that added together give a palindrome (31813).

The spelling of 1581216001 in words is "one billion, five hundred eighty-one million, two hundred sixteen thousand, one".