1581609901 has 2 divisors, whose sum is σ = 1581609902. Its totient is φ = 1581609900.

The previous prime is 1581609889. The next prime is 1581609919. The reversal of 1581609901 is 1099061851.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1370924676 + 210685225 = 37026^2 + 14515^2 .

It is an emirp because it is prime and its reverse (1099061851) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1581609901 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1581409901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 790804950 + 790804951.

It is an arithmetic number, because the mean of its divisors is an integer number (790804951).

Almost surely, 2^1581609901 is an apocalyptic number.

It is an amenable number.

1581609901 is a deficient number, since it is larger than the sum of its proper divisors (1).

1581609901 is an equidigital number, since it uses as much as digits as its factorization.

1581609901 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 19440, while the sum is 40.

The square root of 1581609901 is about 39769.4594003992. The cubic root of 1581609901 is about 1165.1087352689.

The spelling of 1581609901 in words is "one billion, five hundred eighty-one million, six hundred nine thousand, nine hundred one".