21612413 has 2 divisors, whose sum is σ = 21612414. Its totient is φ = 21612412.

The previous prime is 21612397. The next prime is 21612431. The reversal of 21612413 is 31421612.

Together with next prime (21612431) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18292729 + 3319684 = 4277^2 + 1822^2 .

It is a cyclic number.

It is not a de Polignac number, because 21612413 - 2⁴ = 21612397 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21612013) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10806206 + 10806207.

It is an arithmetic number, because the mean of its divisors is an integer number (10806207).

Almost surely, 2^21612413 is an apocalyptic number.

It is an amenable number.

21612413 is a deficient number, since it is larger than the sum of its proper divisors (1).

21612413 is an equidigital number, since it uses as much as digits as its factorization.

21612413 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 288, while the sum is 20.

The square root of 21612413 is about 4648.9152498190. The cubic root of 21612413 is about 278.5486679879.

The spelling of 21612413 in words is "twenty-one million, six hundred twelve thousand, four hundred thirteen".