21912013 has 2 divisors, whose sum is σ = 21912014. Its totient is φ = 21912012.

The previous prime is 21911987. The next prime is 21912017. The reversal of 21912013 is 31021912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19342404 + 2569609 = 4398^2 + 1603^2 .

It is a cyclic number.

It is not a de Polignac number, because 21912013 - 2¹³ = 21903821 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21912017) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10956006 + 10956007.

It is an arithmetic number, because the mean of its divisors is an integer number (10956007).

Almost surely, 2^21912013 is an apocalyptic number.

It is an amenable number.

21912013 is a deficient number, since it is larger than the sum of its proper divisors (1).

21912013 is an equidigital number, since it uses as much as digits as its factorization.

21912013 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 108, while the sum is 19.

The square root of 21912013 is about 4681.0269172480. The cubic root of 21912013 is about 279.8298839105.

Adding to 21912013 its reverse (31021912), we get a palindrome (52933925).

The spelling of 21912013 in words is "twenty-one million, nine hundred twelve thousand, thirteen".