21661532655312 has 80 divisors (see below), whose sum is σ = 61059688929792. Its totient is φ = 6562643660160.

The previous prime is 21661532655281. The next prime is 21661532655313. The reversal of 21661532655312 is 21355623516612.

It is a super-3 number, since 3×21661532655312³ (a number of 41 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21661532655313) 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, 2171628 + ... + 6931019.

Almost surely, 2^{21661532655312} is an apocalyptic number.

21661532655312 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21661532655312 is an abundant number, since it is smaller than the sum of its proper divisors (39398156274480).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21661532655312 is a wasteful number, since it uses less digits than its factorization.

21661532655312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9107176 (or 9107170 counting only the distinct ones).

The product of its digits is 1944000, while the sum is 48.

The spelling of 21661532655312 in words is "twenty-one trillion, six hundred sixty-one billion, five hundred thirty-two million, six hundred fifty-five thousand, three hundred twelve".