21660541 has 8 divisors (see below), whose sum is σ = 24785024. Its totient is φ = 18543600.

The previous prime is 21660523. The next prime is 21660559. The reversal of 21660541 is 14506612.

It is an interprime number because it is at equal distance from previous prime (21660523) and next prime (21660559).

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 21660541 - 2²¹ = 19563389 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21660521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7216 + ... + 9766.

It is an arithmetic number, because the mean of its divisors is an integer number (3098128).

Almost surely, 2^21660541 is an apocalyptic number.

It is an amenable number.

21660541 is a deficient number, since it is larger than the sum of its proper divisors (3124483).

21660541 is a wasteful number, since it uses less digits than its factorization.

21660541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3771.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 21660541 is about 4654.0886325896. The cubic root of 21660541 is about 278.7552784431.

It can be divided in two parts, 21660 and 541, that added together give a square (22201 = 149²).

The spelling of 21660541 in words is "twenty-one million, six hundred sixty thousand, five hundred forty-one".