21666154105 has 8 divisors (see below), whose sum is σ = 26149671432. Its totient is φ = 17232732288.

The previous prime is 21666154087. The next prime is 21666154117. The reversal of 21666154105 is 50145166612.

It can be written as a sum of positive squares in 4 ways, for example, as 5871697129 + 15794456976 = 76627^2 + 125676^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21666154105 - 2¹⁷ = 21666023033 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12522924 + ... + 12524653.

It is an arithmetic number, because the mean of its divisors is an integer number (3268708929).

Almost surely, 2^21666154105 is an apocalyptic number.

It is an amenable number.

21666154105 is a deficient number, since it is larger than the sum of its proper divisors (4483517327).

21666154105 is a wasteful number, since it uses less digits than its factorization.

21666154105 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25047755.

The product of its (nonzero) digits is 43200, while the sum is 37.

The spelling of 21666154105 in words is "twenty-one billion, six hundred sixty-six million, one hundred fifty-four thousand, one hundred five".