21661100465543 has 64 divisors (see below), whose sum is σ = 27839317939200. Its totient is φ = 16706089008000.

The previous prime is 21661100465497. The next prime is 21661100465597. The reversal of 21661100465543 is 34556400116612.

It is not a de Polignac number, because 21661100465543 - 2¹⁰ = 21661100464519 is a prime.

It is a hoax number, since the sum of its digits (44) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21661100465494 and 21661100465503.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21661100461543) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1422537896 + ... + 1422553122.

It is an arithmetic number, because the mean of its divisors is an integer number (434989342800).

Almost surely, 2^{21661100465543} is an apocalyptic number.

21661100465543 is a deficient number, since it is larger than the sum of its proper divisors (6178217473657).

21661100465543 is a wasteful number, since it uses less digits than its factorization.

21661100465543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19093 (or 19079 counting only the distinct ones).

The product of its (nonzero) digits is 518400, while the sum is 44.

The spelling of 21661100465543 in words is "twenty-one trillion, six hundred sixty-one billion, one hundred million, four hundred sixty-five thousand, five hundred forty-three".