21000007 has 8 divisors (see below), whose sum is σ = 24034976. Its totient is φ = 17973792.

The previous prime is 20999999. The next prime is 21000037. The reversal of 21000007 is 70000012.

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 21000007 - 2³ = 20999999 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20999957 and 21000002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000037) 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, 4213 + ... + 7729.

It is an arithmetic number, because the mean of its divisors is an integer number (3004372).

Almost surely, 2^21000007 is an apocalyptic number.

21000007 is a deficient number, since it is larger than the sum of its proper divisors (3034969).

21000007 is an equidigital number, since it uses as much as digits as its factorization.

21000007 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4377.

The product of its (nonzero) digits is 14, while the sum is 10.

The square root of 21000007 is about 4582.5764587184. The cubic root of 21000007 is about 275.8924482928.

Adding to 21000007 its reverse (70000012), we get a palindrome (91000019).

The spelling of 21000007 in words is "twenty-one million, seven", and thus it is an aban number and an uban number.