21661042116013 has 4 divisors (see below), whose sum is σ = 21816876951520. Its totient is φ = 21505207280508.

The previous prime is 21661042115989. The next prime is 21661042116019. The reversal of 21661042116013 is 31061124016612.

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 21661042116013 - 2⁵ = 21661042115981 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 21661042116013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21661042116019) 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, 77917417545 + ... + 77917417822.

It is an arithmetic number, because the mean of its divisors is an integer number (5454219237880).

Almost surely, 2^{21661042116013} is an apocalyptic number.

It is an amenable number.

21661042116013 is a deficient number, since it is larger than the sum of its proper divisors (155834835507).

21661042116013 is a wasteful number, since it uses less digits than its factorization.

21661042116013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 155834835506.

The product of its (nonzero) digits is 10368, while the sum is 34.

The spelling of 21661042116013 in words is "twenty-one trillion, six hundred sixty-one billion, forty-two million, one hundred sixteen thousand, thirteen".