21678005 has 8 divisors (see below), whose sum is σ = 26058624. Its totient is φ = 17312400.

The previous prime is 21678001. The next prime is 21678037. The reversal of 21678005 is 50087612.

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

It is not a de Polignac number, because 21678005 - 2² = 21678001 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 (21678001) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 281 + ... + 6590.

It is an arithmetic number, because the mean of its divisors is an integer number (3257328).

Almost surely, 2^21678005 is an apocalyptic number.

It is an amenable number.

21678005 is a deficient number, since it is larger than the sum of its proper divisors (4380619).

21678005 is an equidigital number, since it uses as much as digits as its factorization.

21678005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7507.

The product of its (nonzero) digits is 3360, while the sum is 29.

The square root of 21678005 is about 4655.9644543317. The cubic root of 21678005 is about 278.8301746092.

The spelling of 21678005 in words is "twenty-one million, six hundred seventy-eight thousand, five".