21661031331363 has 16 divisors (see below), whose sum is σ = 29813324092416. Its totient is φ = 13974722178720.

The previous prime is 21661031331323. The next prime is 21661031331409. The reversal of 21661031331363 is 36313313016612.

It is not a de Polignac number, because 21661031331363 - 2⁶ = 21661031331299 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21661031331323) 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, 8887681 + ... + 11059517.

It is an arithmetic number, because the mean of its divisors is an integer number (1863332755776).

Almost surely, 2^{21661031331363} is an apocalyptic number.

21661031331363 is a deficient number, since it is larger than the sum of its proper divisors (8152292761053).

21661031331363 is a wasteful number, since it uses less digits than its factorization.

21661031331363 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2279114.

The product of its (nonzero) digits is 104976, while the sum is 39.

Adding to 21661031331363 its reverse (36313313016612), we get a palindrome (57974344347975).

The spelling of 21661031331363 in words is "twenty-one trillion, six hundred sixty-one billion, thirty-one million, three hundred thirty-one thousand, three hundred sixty-three".