21045553015213 has 4 divisors (see below), whose sum is σ = 21154597331548. Its totient is φ = 20936508698880.

The previous prime is 21045553015153. The next prime is 21045553015271. The reversal of 21045553015213 is 31251035554012.

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 7359267563209 + 13686285452004 = 2712797^2 + 3699498^2 .

It is a cyclic number.

It is not a de Polignac number, because 21045553015213 - 2¹⁷ = 21045552884141 is a prime.

It is a super-2 number, since 2×21045553015213² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21045553015273) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 54522157878 + ... + 54522158263.

It is an arithmetic number, because the mean of its divisors is an integer number (5288649332887).

Almost surely, 2^{21045553015213} is an apocalyptic number.

It is an amenable number.

21045553015213 is a deficient number, since it is larger than the sum of its proper divisors (109044316335).

21045553015213 is a wasteful number, since it uses less digits than its factorization.

21045553015213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 109044316334.

The product of its (nonzero) digits is 90000, while the sum is 37.

Adding to 21045553015213 its reverse (31251035554012), we get a palindrome (52296588569225).

The spelling of 21045553015213 in words is "twenty-one trillion, forty-five billion, five hundred fifty-three million, fifteen thousand, two hundred thirteen".