21070513 has 2 divisors, whose sum is σ = 21070514. Its totient is φ = 21070512.

The previous prime is 21070481. The next prime is 21070541. The reversal of 21070513 is 31507012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12873744 + 8196769 = 3588^2 + 2863^2 .

It is a cyclic number.

It is not a de Polignac number, because 21070513 - 2⁵ = 21070481 is a prime.

It is equal to p_1334152 and since 21070513 and 1334152 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (21070583) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10535256 + 10535257.

It is an arithmetic number, because the mean of its divisors is an integer number (10535257).

Almost surely, 2^21070513 is an apocalyptic number.

It is an amenable number.

21070513 is a deficient number, since it is larger than the sum of its proper divisors (1).

21070513 is an equidigital number, since it uses as much as digits as its factorization.

21070513 is an odious number, because the sum of its binary digits is odd.

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

The square root of 21070513 is about 4590.2628465045. The cubic root of 21070513 is about 276.2008663461.

Adding to 21070513 its reverse (31507012), we get a palindrome (52577525).

The spelling of 21070513 in words is "twenty-one million, seventy thousand, five hundred thirteen".