21666346512 has 40 divisors (see below), whose sum is σ = 57162281856. Its totient is φ = 7068452736.

The previous prime is 21666346511. The next prime is 21666346531. The reversal of 21666346512 is 21564366612.

It is a super-2 number, since 2×21666346512² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21666346511) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4799683 + ... + 4804194.

Almost surely, 2^21666346512 is an apocalyptic number.

It is an amenable number.

21666346512 is an abundant number, since it is smaller than the sum of its proper divisors (35495935344).

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

21666346512 is a wasteful number, since it uses less digits than its factorization.

21666346512 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9603935 (or 9603929 counting only the distinct ones).

The product of its digits is 311040, while the sum is 42.

It can be divided in two parts, 216663 and 46512, that added together give a triangular number (263175 = T₇₂₅).

The spelling of 21666346512 in words is "twenty-one billion, six hundred sixty-six million, three hundred forty-six thousand, five hundred twelve".