21541687 has 8 divisors (see below), whose sum is σ = 23229360. Its totient is φ = 19909440.

The previous prime is 21541661. The next prime is 21541697. The reversal of 21541687 is 78614512.

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 21541687 - 2¹⁵ = 21508919 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 (21541607) 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, 13048 + ... + 14605.

It is an arithmetic number, because the mean of its divisors is an integer number (2903670).

Almost surely, 2^21541687 is an apocalyptic number.

21541687 is a deficient number, since it is larger than the sum of its proper divisors (1687673).

21541687 is a wasteful number, since it uses less digits than its factorization.

21541687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27713.

The product of its digits is 13440, while the sum is 34.

The square root of 21541687 is about 4641.3022956924. The cubic root of 21541687 is about 278.2444884382.

The spelling of 21541687 in words is "twenty-one million, five hundred forty-one thousand, six hundred eighty-seven".