21215426947237 has 2 divisors, whose sum is σ = 21215426947238. Its totient is φ = 21215426947236.

The previous prime is 21215426947199. The next prime is 21215426947249. The reversal of 21215426947237 is 73274962451212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19684963527076 + 1530463420161 = 4436774^2 + 1237119^2 .

It is a cyclic number.

It is not a de Polignac number, because 21215426947237 - 2¹¹ = 21215426945189 is a prime.

It is a super-3 number, since 3×21215426947237³ (a number of 41 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21215426947837) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10607713473618 + 10607713473619.

It is an arithmetic number, because the mean of its divisors is an integer number (10607713473619).

Almost surely, 2^{21215426947237} is an apocalyptic number.

It is an amenable number.

21215426947237 is a deficient number, since it is larger than the sum of its proper divisors (1).

21215426947237 is an equidigital number, since it uses as much as digits as its factorization.

21215426947237 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10160640, while the sum is 55.

The spelling of 21215426947237 in words is "twenty-one trillion, two hundred fifteen billion, four hundred twenty-six million, nine hundred forty-seven thousand, two hundred thirty-seven".