21667371 has 8 divisors (see below), whose sum is σ = 31516224. Its totient is φ = 13131720.

The previous prime is 21667351. The next prime is 21667381. The reversal of 21667371 is 17376612.

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

It is not a de Polignac number, because 21667371 - 2⁶ = 21667307 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33), and also a Moran number because the ratio is a prime number: 656587 = 21667371 / (2 + 1 + 6 + 6 + 7 + 3 + 7 + 1).

It is not an unprimeable number, because it can be changed into a prime (21667351) 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, 328261 + ... + 328326.

It is an arithmetic number, because the mean of its divisors is an integer number (3939528).

Almost surely, 2^21667371 is an apocalyptic number.

21667371 is a deficient number, since it is larger than the sum of its proper divisors (9848853).

21667371 is a wasteful number, since it uses less digits than its factorization.

21667371 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 656601.

The product of its digits is 10584, while the sum is 33.

The square root of 21667371 is about 4654.8223381779. The cubic root of 21667371 is about 278.7845743946.

The spelling of 21667371 in words is "twenty-one million, six hundred sixty-seven thousand, three hundred seventy-one".