1581402649 has 2 divisors, whose sum is σ = 1581402650. Its totient is φ = 1581402648.

The previous prime is 1581402619. The next prime is 1581402703. The reversal of 1581402649 is 9462041851.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1564756249 + 16646400 = 39557^2 + 4080^2 .

It is a cyclic number.

It is not a de Polignac number, because 1581402649 - 2⁵ = 1581402617 is a prime.

It is not a weakly prime, because it can be changed into another prime (1581402619) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 790701324 + 790701325.

It is an arithmetic number, because the mean of its divisors is an integer number (790701325).

Almost surely, 2^1581402649 is an apocalyptic number.

It is an amenable number.

1581402649 is a deficient number, since it is larger than the sum of its proper divisors (1).

1581402649 is an equidigital number, since it uses as much as digits as its factorization.

1581402649 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 69120, while the sum is 40.

The square root of 1581402649 is about 39766.8536472274. The cubic root of 1581402649 is about 1165.0578416270.

The spelling of 1581402649 in words is "one billion, five hundred eighty-one million, four hundred two thousand, six hundred forty-nine".