9918212890625 has 36 divisors (see below), whose sum is σ = 13351440429684. Its totient is φ = 7324218750000.

The previous prime is 9918212890583. The next prime is 9918212890631. The reversal of 9918212890625 is 5260982128199.

It is a happy number.

It can be written as a sum of positive squares in 18 ways, for example, as 3311220744976 + 6606992145649 = 1819676^2 + 2570407^2 .

It is an automorphic number since its square, 98370946943759918212890625, ends in 9918212890625.

It is a trimorphic number since its cube, 975663994040587567724287509918212890625, ends in 9918212890625.

It is not a de Polignac number, because 9918212890625 - 2²⁴ = 9918196113409 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 762939453119 + ... + 762939453131.

It is an arithmetic number, because the mean of its divisors is an integer number (370873345269).

Almost surely, 2^{9918212890625} is an apocalyptic number.

It is an amenable number.

9918212890625 is a deficient number, since it is larger than the sum of its proper divisors (3433227539059).

9918212890625 is an frugal number, since it uses more digits than its factorization.

9918212890625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98 (or 18 counting only the distinct ones).

The product of its (nonzero) digits is 11197440, while the sum is 62.

The spelling of 9918212890625 in words is "nine trillion, nine hundred eighteen billion, two hundred twelve million, eight hundred ninety thousand, six hundred twenty-five".