21661031332063 has 4 divisors (see below), whose sum is σ = 21699920078280. Its totient is φ = 21622142585848.

The previous prime is 21661031332049. The next prime is 21661031332081. The reversal of 21661031332063 is 36023313016612.

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 21661031332063 - 2³³ = 21652441397471 is a prime.

It is a super-2 number, since 2×21661031332063² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21661031332463) 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, 19444372273 + ... + 19444373386.

It is an arithmetic number, because the mean of its divisors is an integer number (5424980019570).

Almost surely, 2^{21661031332063} is an apocalyptic number.

21661031332063 is a deficient number, since it is larger than the sum of its proper divisors (38888746217).

21661031332063 is an equidigital number, since it uses as much as digits as its factorization.

21661031332063 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38888746216.

The product of its (nonzero) digits is 69984, while the sum is 37.

Adding to 21661031332063 its reverse (36023313016612), we get a palindrome (57684344348675).

The spelling of 21661031332063 in words is "twenty-one trillion, six hundred sixty-one billion, thirty-one million, three hundred thirty-two thousand, sixty-three".