21751013 has 4 divisors (see below), whose sum is σ = 21773580. Its totient is φ = 21728448.

The previous prime is 21750997. The next prime is 21751019. The reversal of 21751013 is 31015712.

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 4169764 + 17581249 = 2042^2 + 4193^2 .

It is a cyclic number.

It is not a de Polignac number, because 21751013 - 2⁴ = 21750997 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21751019) 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, 9770 + ... + 11787.

It is an arithmetic number, because the mean of its divisors is an integer number (5443395).

Almost surely, 2^21751013 is an apocalyptic number.

It is an amenable number.

21751013 is a deficient number, since it is larger than the sum of its proper divisors (22567).

21751013 is a wasteful number, since it uses less digits than its factorization.

21751013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22566.

The product of its (nonzero) digits is 210, while the sum is 20.

The square root of 21751013 is about 4663.7981302797. The cubic root of 21751013 is about 279.1428421143.

Adding to 21751013 its reverse (31015712), we get a palindrome (52766725).

The spelling of 21751013 in words is "twenty-one million, seven hundred fifty-one thousand, thirteen".