21216420255353 has 4 divisors (see below), whose sum is σ = 21216457647360. Its totient is φ = 21216382863348.

The previous prime is 21216420255341. The next prime is 21216420255377. The reversal of 21216420255353 is 35355202461212.

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 21216420255353 - 2⁸ = 21216420255097 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 21216420255353.

It is not an unprimeable number, because it can be changed into a prime (21216420255053) 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, 17831573 + ... + 18984146.

It is an arithmetic number, because the mean of its divisors is an integer number (5304114411840).

Almost surely, 2^{21216420255353} is an apocalyptic number.

It is an amenable number.

21216420255353 is a deficient number, since it is larger than the sum of its proper divisors (37392007).

21216420255353 is an equidigital number, since it uses as much as digits as its factorization.

21216420255353 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37392006.

The product of its (nonzero) digits is 432000, while the sum is 41.

The spelling of 21216420255353 in words is "twenty-one trillion, two hundred sixteen billion, four hundred twenty million, two hundred fifty-five thousand, three hundred fifty-three".