21213612366431 has 4 divisors (see below), whose sum is σ = 21219331866600. Its totient is φ = 21207892866264.

The previous prime is 21213612366343. The next prime is 21213612366469. The reversal of 21213612366431 is 13466321631212.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21213612366431 is a prime.

It is a super-2 number, since 2×21213612366431² (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 (21213612366731) 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, 2859744521 + ... + 2859751938.

It is an arithmetic number, because the mean of its divisors is an integer number (5304832966650).

Almost surely, 2^{21213612366431} is an apocalyptic number.

21213612366431 is a deficient number, since it is larger than the sum of its proper divisors (5719500169).

21213612366431 is an equidigital number, since it uses as much as digits as its factorization.

21213612366431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5719500168.

The product of its digits is 186624, while the sum is 41.

Adding to 21213612366431 its reverse (13466321631212), we get a palindrome (34679933997643).

The spelling of 21213612366431 in words is "twenty-one trillion, two hundred thirteen billion, six hundred twelve million, three hundred sixty-six thousand, four hundred thirty-one".