1538994047581 has 2 divisors, whose sum is σ = 1538994047582. Its totient is φ = 1538994047580.

The previous prime is 1538994047561. The next prime is 1538994047629. The reversal of 1538994047581 is 1857404998351.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1431731902500 + 107262145081 = 1196550^2 + 327509^2 .

It is a cyclic number.

It is not a de Polignac number, because 1538994047581 - 2¹⁹ = 1538993523293 is a prime.

It is a super-2 number, since 2×1538994047581² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1538994047531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 769497023790 + 769497023791.

It is an arithmetic number, because the mean of its divisors is an integer number (769497023791).

Almost surely, 2^{1538994047581} is an apocalyptic number.

It is an amenable number.

1538994047581 is a deficient number, since it is larger than the sum of its proper divisors (1).

1538994047581 is an equidigital number, since it uses as much as digits as its factorization.

1538994047581 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 43545600, while the sum is 64.

The spelling of 1538994047581 in words is "one trillion, five hundred thirty-eight billion, nine hundred ninety-four million, forty-seven thousand, five hundred eighty-one".