21217323053 has 4 divisors (see below), whose sum is σ = 21507971388. Its totient is φ = 20926674720.

The previous prime is 21217323019. The next prime is 21217323077. The reversal of 21217323053 is 35032371212.

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 16240443844 + 4976879209 = 127438^2 + 70547^2 .

It is a cyclic number.

It is not a de Polignac number, because 21217323053 - 2¹⁰ = 21217322029 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21217323653) 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, 145324058 + ... + 145324203.

It is an arithmetic number, because the mean of its divisors is an integer number (5376992847).

Almost surely, 2^21217323053 is an apocalyptic number.

It is an amenable number.

21217323053 is a deficient number, since it is larger than the sum of its proper divisors (290648335).

21217323053 is an equidigital number, since it uses as much as digits as its factorization.

21217323053 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 290648334.

The product of its (nonzero) digits is 7560, while the sum is 29.

Adding to 21217323053 its reverse (35032371212), we get a palindrome (56249694265).

The spelling of 21217323053 in words is "twenty-one billion, two hundred seventeen million, three hundred twenty-three thousand, fifty-three".