11111478921 has 27 divisors (see below), whose sum is σ = 16470141493. Its totient is φ = 7218545280.

The previous prime is 11111478887. The next prime is 11111478929. The reversal of 11111478921 is 12987411111.

The square root of 11111478921 is 105411.

It is a perfect power (a square), and thus also a powerful number.

11111478921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 30969225 + 11080509696 = 5565^2 + 105264^2 .

It is not a de Polignac number, because 11111478921 - 2³¹ = 8963995273 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (11111478929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 12965125 + ... + 12965981.

Almost surely, 2^11111478921 is an apocalyptic number.

11111478921 is the 105411-st square number.

11111478921 is the 52706-th centered octagonal number.

It is an amenable number.

11111478921 is a deficient number, since it is larger than the sum of its proper divisors (5358662572).

11111478921 is an frugal number, since it uses more digits than its factorization.

11111478921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1802 (or 901 counting only the distinct ones).

The product of its digits is 4032, while the sum is 36.

Multiplying 11111478921 by its sum of digits (36), we get a square (400013241156 = 632466²).

The spelling of 11111478921 in words is "eleven billion, one hundred eleven million, four hundred seventy-eight thousand, nine hundred twenty-one".