21121535213 has 4 divisors (see below), whose sum is σ = 21143023008. Its totient is φ = 21100047420.

The previous prime is 21121535209. The next prime is 21121535219. The reversal of 21121535213 is 31253512112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21121535213 - 2² = 21121535209 is a prime.

It is a super-2 number, since 2×21121535213² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121535219) 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, 10742423 + ... + 10744388.

It is an arithmetic number, because the mean of its divisors is an integer number (5285755752).

Almost surely, 2^21121535213 is an apocalyptic number.

It is an amenable number.

21121535213 is a deficient number, since it is larger than the sum of its proper divisors (21487795).

21121535213 is an equidigital number, since it uses as much as digits as its factorization.

21121535213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21487794.

The product of its digits is 1800, while the sum is 26.

The spelling of 21121535213 in words is "twenty-one billion, one hundred twenty-one million, five hundred thirty-five thousand, two hundred thirteen".