21310507 has 4 divisors (see below), whose sum is σ = 21463960. Its totient is φ = 21157056.

The previous prime is 21310493. The next prime is 21310517. The reversal of 21310507 is 70501312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21310507 - 2¹⁹ = 20786219 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21310517) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 76518 + ... + 76795.

It is an arithmetic number, because the mean of its divisors is an integer number (5365990).

Almost surely, 2^21310507 is an apocalyptic number.

21310507 is a deficient number, since it is larger than the sum of its proper divisors (153453).

21310507 is a wasteful number, since it uses less digits than its factorization.

21310507 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 153452.

The product of its (nonzero) digits is 210, while the sum is 19.

The square root of 21310507 is about 4616.3304691064. The cubic root of 21310507 is about 277.2455563417.

Adding to 21310507 its reverse (70501312), we get a palindrome (91811819).

The spelling of 21310507 in words is "twenty-one million, three hundred ten thousand, five hundred seven".