21121000455623 has 4 divisors (see below), whose sum is σ = 21171169103208. Its totient is φ = 21070831808040.

The previous prime is 21121000455593. The next prime is 21121000455677. The reversal of 21121000455623 is 32655400012112.

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

It is a cyclic number.

It is not a de Polignac number, because 21121000455623 - 2⁸ = 21121000455367 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 21121000455623.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121000455923) 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, 25084323161 + ... + 25084324002.

It is an arithmetic number, because the mean of its divisors is an integer number (5292792275802).

Almost surely, 2^{21121000455623} is an apocalyptic number.

21121000455623 is a deficient number, since it is larger than the sum of its proper divisors (50168647585).

21121000455623 is an equidigital number, since it uses as much as digits as its factorization.

21121000455623 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50168647584.

The product of its (nonzero) digits is 14400, while the sum is 32.

Adding to 21121000455623 its reverse (32655400012112), we get a palindrome (53776400467735).

The spelling of 21121000455623 in words is "twenty-one trillion, one hundred twenty-one billion, four hundred fifty-five thousand, six hundred twenty-three".