21210507 has 12 divisors (see below), whose sum is σ = 30798664. Its totient is φ = 14065920.

The previous prime is 21210499. The next prime is 21210521. The reversal of 21210507 is 70501212.

It is not a de Polignac number, because 21210507 - 2³ = 21210499 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21210507.

It is not an unprimeable number, because it can be changed into a prime (21210557) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4369 + ... + 7842.

Almost surely, 2^21210507 is an apocalyptic number.

21210507 is a deficient number, since it is larger than the sum of its proper divisors (9588157).

21210507 is a wasteful number, since it uses less digits than its factorization.

21210507 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12410 (or 12407 counting only the distinct ones).

The product of its (nonzero) digits is 140, while the sum is 18.

The square root of 21210507 is about 4605.4866192401. The cubic root of 21210507 is about 276.8112160565.

Adding to 21210507 its reverse (70501212), we get a palindrome (91711719).

The spelling of 21210507 in words is "twenty-one million, two hundred ten thousand, five hundred seven".