13540021991 has 2 divisors, whose sum is σ = 13540021992. Its totient is φ = 13540021990.

The previous prime is 13540021973. The next prime is 13540022021. The reversal of 13540021991 is 19912004531.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 13540021991 - 2¹⁴ = 13540005607 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (13540021591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6770010995 + 6770010996.

It is an arithmetic number, because the mean of its divisors is an integer number (6770010996).

Almost surely, 2^13540021991 is an apocalyptic number.

13540021991 is a deficient number, since it is larger than the sum of its proper divisors (1).

13540021991 is an equidigital number, since it uses as much as digits as its factorization.

13540021991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9720, while the sum is 35.

The spelling of 13540021991 in words is "thirteen billion, five hundred forty million, twenty-one thousand, nine hundred ninety-one".