21670005 has 24 divisors (see below), whose sum is σ = 40334112. Its totient is φ = 9905952.

The previous prime is 21670003. The next prime is 21670007. The reversal of 21670005 is 50007612.

It is an interprime number because it is at equal distance from previous prime (21670003) and next prime (21670007).

It is not a de Polignac number, because 21670005 - 2¹ = 21670003 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21670003) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 14007 + ... + 15476.

It is an arithmetic number, because the mean of its divisors is an integer number (1680588).

Almost surely, 2^21670005 is an apocalyptic number.

It is an amenable number.

21670005 is a deficient number, since it is larger than the sum of its proper divisors (18664107).

21670005 is a wasteful number, since it uses less digits than its factorization.

21670005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29505 (or 29498 counting only the distinct ones).

The product of its (nonzero) digits is 420, while the sum is 21.

The square root of 21670005 is about 4655.1052619678. The cubic root of 21670005 is about 278.7958707783.

Adding to 21670005 its reverse (50007612), we get a palindrome (71677617).

The spelling of 21670005 in words is "twenty-one million, six hundred seventy thousand, five".