21313507 has 4 divisors (see below), whose sum is σ = 21332736. Its totient is φ = 21294280.

The previous prime is 21313493. The next prime is 21313531. The reversal of 21313507 is 70531312.

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 21313507 - 2⁷ = 21313379 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21313547) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7843 + ... + 10204.

It is an arithmetic number, because the mean of its divisors is an integer number (5333184).

Almost surely, 2^21313507 is an apocalyptic number.

21313507 is a deficient number, since it is larger than the sum of its proper divisors (19229).

21313507 is a wasteful number, since it uses less digits than its factorization.

21313507 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19228.

The product of its (nonzero) digits is 630, while the sum is 22.

The square root of 21313507 is about 4616.6553910813. The cubic root of 21313507 is about 277.2585655370.

Adding to 21313507 its reverse (70531312), we get a palindrome (91844819).

The spelling of 21313507 in words is "twenty-one million, three hundred thirteen thousand, five hundred seven".