11021997978 has 24 divisors (see below), whose sum is σ = 24331582548. Its totient is φ = 3604678272.

The previous prime is 11021997977. The next prime is 11021997997. The reversal of 11021997978 is 87979912011.

It can be written as a sum of positive squares in 2 ways, for example, as 8466392169 + 2555605809 = 92013^2 + 50553^2 .

It is not an unprimeable number, because it can be changed into a prime (11021997977) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5775775 + ... + 5777682.

Almost surely, 2^11021997978 is an apocalyptic number.

11021997978 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

11021997978 is an abundant number, since it is smaller than the sum of its proper divisors (13309584570).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

11021997978 is a wasteful number, since it uses less digits than its factorization.

11021997978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11553518 (or 11553515 counting only the distinct ones).

The product of its (nonzero) digits is 571536, while the sum is 54.

The spelling of 11021997978 in words is "eleven billion, twenty-one million, nine hundred ninety-seven thousand, nine hundred seventy-eight".