21022513 has 4 divisors (see below), whose sum is σ = 21176100. Its totient is φ = 20868928.

The previous prime is 21022471. The next prime is 21022517. The reversal of 21022513 is 31522012.

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

It can be written as a sum of positive squares in 2 ways, for example, as 4765489 + 16257024 = 2183^2 + 4032^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21022513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21022517) 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, 76588 + ... + 76861.

It is an arithmetic number, because the mean of its divisors is an integer number (5294025).

Almost surely, 2^21022513 is an apocalyptic number.

It is an amenable number.

21022513 is a deficient number, since it is larger than the sum of its proper divisors (153587).

21022513 is a wasteful number, since it uses less digits than its factorization.

21022513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153586.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21022513 is about 4585.0314066536. The cubic root of 21022513 is about 275.9909723645.

Adding to 21022513 its reverse (31522012), we get a palindrome (52544525).

The spelling of 21022513 in words is "twenty-one million, twenty-two thousand, five hundred thirteen".