21660471 has 12 divisors (see below), whose sum is σ = 35757072. Its totient is φ = 12377376.

The previous prime is 21660469. The next prime is 21660473. The reversal of 21660471 is 17406612.

It is an interprime number because it is at equal distance from previous prime (21660469) and next prime (21660473).

It is not a de Polignac number, because 21660471 - 2¹ = 21660469 is a prime.

It is a super-3 number, since 3×21660471³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21660473) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 171846 + ... + 171971.

It is an arithmetic number, because the mean of its divisors is an integer number (2979756).

Almost surely, 2^21660471 is an apocalyptic number.

21660471 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21660471 is a deficient number, since it is larger than the sum of its proper divisors (14096601).

21660471 is a wasteful number, since it uses less digits than its factorization.

21660471 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 343830 (or 343827 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 21660471 is about 4654.0811123142. The cubic root of 21660471 is about 278.7549781599.

The spelling of 21660471 in words is "twenty-one million, six hundred sixty thousand, four hundred seventy-one".