21007005 has 16 divisors (see below), whose sum is σ = 34393920. Its totient is φ = 10942848.

The previous prime is 21007001. The next prime is 21007013. The reversal of 21007005 is 50070012.

It is a happy number.

It is not a de Polignac number, because 21007005 - 2² = 21007001 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21007001) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15640 + ... + 16929.

It is an arithmetic number, because the mean of its divisors is an integer number (2149620).

Almost surely, 2^21007005 is an apocalyptic number.

It is an amenable number.

21007005 is a deficient number, since it is larger than the sum of its proper divisors (13386915).

21007005 is a wasteful number, since it uses less digits than its factorization.

21007005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32620.

The product of its (nonzero) digits is 70, while the sum is 15.

The square root of 21007005 is about 4583.3399393892. The cubic root of 21007005 is about 275.9230908371.

Adding to 21007005 its reverse (50070012), we get a palindrome (71077017).

The spelling of 21007005 in words is "twenty-one million, seven thousand, five".