21213545023561 has 8 divisors (see below), whose sum is σ = 23144396536800. Its totient is φ = 19283084747040.

The previous prime is 21213545023537. The next prime is 21213545023603. The reversal of 21213545023561 is 16532054531212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21213545023561 - 2⁵ = 21213545023529 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21213545023061) 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 7 ways as a sum of consecutive naturals, for example, 97695796 + ... + 97912693.

It is an arithmetic number, because the mean of its divisors is an integer number (2893049567100).

Almost surely, 2^{21213545023561} is an apocalyptic number.

It is an amenable number.

21213545023561 is a deficient number, since it is larger than the sum of its proper divisors (1930851513239).

21213545023561 is a wasteful number, since it uses less digits than its factorization.

21213545023561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 195618359.

The product of its (nonzero) digits is 216000, while the sum is 40.

Adding to 21213545023561 its reverse (16532054531212), we get a palindrome (37745599554773).

The spelling of 21213545023561 in words is "twenty-one trillion, two hundred thirteen billion, five hundred forty-five million, twenty-three thousand, five hundred sixty-one".