21661353013103 has 4 divisors (see below), whose sum is σ = 21661362623808. Its totient is φ = 21661343402400.

The previous prime is 21661353013081. The next prime is 21661353013109. The reversal of 21661353013103 is 30131035316612.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21661353013103 - 2⁸ = 21661353012847 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 (21661353013109) 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, 608903 + ... + 6610103.

It is an arithmetic number, because the mean of its divisors is an integer number (5415340655952).

Almost surely, 2^{21661353013103} is an apocalyptic number.

21661353013103 is a deficient number, since it is larger than the sum of its proper divisors (9610705).

21661353013103 is an equidigital number, since it uses as much as digits as its factorization.

21661353013103 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9610704.

The product of its (nonzero) digits is 29160, while the sum is 35.

Adding to 21661353013103 its reverse (30131035316612), we get a palindrome (51792388329715).

The spelling of 21661353013103 in words is "twenty-one trillion, six hundred sixty-one billion, three hundred fifty-three million, thirteen thousand, one hundred three".