21113203252661 has 16 divisors (see below), whose sum is σ = 22901465664000. Its totient is φ = 19348525915968.

The previous prime is 21113203252657. The next prime is 21113203252679. The reversal of 21113203252661 is 16625230231112.

It is a cyclic number.

It is not a de Polignac number, because 21113203252661 - 2² = 21113203252657 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 (21113203252651) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1079420 + ... + 6587226.

It is an arithmetic number, because the mean of its divisors is an integer number (1431341604000).

Almost surely, 2^{21113203252661} is an apocalyptic number.

It is an amenable number.

21113203252661 is a deficient number, since it is larger than the sum of its proper divisors (1788262411339).

21113203252661 is a wasteful number, since it uses less digits than its factorization.

21113203252661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5509948.

The product of its (nonzero) digits is 25920, while the sum is 35.

Adding to 21113203252661 its reverse (16625230231112), we get a palindrome (37738433483773).

The spelling of 21113203252661 in words is "twenty-one trillion, one hundred thirteen billion, two hundred three million, two hundred fifty-two thousand, six hundred sixty-one".