21540214013 has 4 divisors (see below), whose sum is σ = 21604131900. Its totient is φ = 21476296128.

The previous prime is 21540214001. The next prime is 21540214057. The reversal of 21540214013 is 31041204512.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9093911044 + 12446302969 = 95362^2 + 111563^2 .

It is a cyclic number.

It is not a de Polignac number, because 21540214013 - 2⁴ = 21540213997 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21540214013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21540214093) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 31958438 + ... + 31959111.

It is an arithmetic number, because the mean of its divisors is an integer number (5401032975).

Almost surely, 2^21540214013 is an apocalyptic number.

It is an amenable number.

21540214013 is a deficient number, since it is larger than the sum of its proper divisors (63917887).

21540214013 is an equidigital number, since it uses as much as digits as its factorization.

21540214013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63917886.

The product of its (nonzero) digits is 960, while the sum is 23.

Adding to 21540214013 its reverse (31041204512), we get a palindrome (52581418525).

The spelling of 21540214013 in words is "twenty-one billion, five hundred forty million, two hundred fourteen thousand, thirteen".