21213612523261 has 2 divisors, whose sum is σ = 21213612523262. Its totient is φ = 21213612523260.

The previous prime is 21213612523253. The next prime is 21213612523303. The reversal of 21213612523261 is 16232521631212.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14680507195225 + 6533105328036 = 3831515^2 + 2555994^2 .

It is a cyclic number.

It is not a de Polignac number, because 21213612523261 - 2³ = 21213612523253 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21213612523261.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21213612523231) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606806261630 + 10606806261631.

It is an arithmetic number, because the mean of its divisors is an integer number (10606806261631).

Almost surely, 2^{21213612523261} is an apocalyptic number.

It is an amenable number.

21213612523261 is a deficient number, since it is larger than the sum of its proper divisors (1).

21213612523261 is an equidigital number, since it uses as much as digits as its factorization.

21213612523261 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 51840, while the sum is 37.

The spelling of 21213612523261 in words is "twenty-one trillion, two hundred thirteen billion, six hundred twelve million, five hundred twenty-three thousand, two hundred sixty-one".