21506211357245 has 8 divisors (see below), whose sum is σ = 25903392119640. Its totient is φ = 17141010091840.

The previous prime is 21506211357221. The next prime is 21506211357289. The reversal of 21506211357245 is 54275311260512.

It can be written as a sum of positive squares in 4 ways, for example, as 67107420601 + 21439103936644 = 259051^2 + 4630238^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21506211357245 - 2¹² = 21506211353149 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21506211357196 and 21506211357205.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7994872766 + ... + 7994875455.

It is an arithmetic number, because the mean of its divisors is an integer number (3237924014955).

Almost surely, 2^{21506211357245} is an apocalyptic number.

It is an amenable number.

21506211357245 is a deficient number, since it is larger than the sum of its proper divisors (4397180762395).

21506211357245 is a wasteful number, since it uses less digits than its factorization.

21506211357245 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15989748495.

The product of its (nonzero) digits is 504000, while the sum is 44.

The spelling of 21506211357245 in words is "twenty-one trillion, five hundred six billion, two hundred eleven million, three hundred fifty-seven thousand, two hundred forty-five".