21245136388 has 36 divisors (see below), whose sum is σ = 43279780572. Its totient is φ = 9098584320.

The previous prime is 21245136379. The next prime is 21245136389. The reversal of 21245136388 is 88363154212.

It can be written as a sum of positive squares in 2 ways, for example, as 20164568004 + 1080568384 = 142002^2 + 32872^2 .

It is a hoax number, since the sum of its digits (43) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21245136389) 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, 243048 + ... + 318688.

It is an arithmetic number, because the mean of its divisors is an integer number (1202216127).

Almost surely, 2^21245136388 is an apocalyptic number.

21245136388 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21245136388 is an abundant number, since it is smaller than the sum of its proper divisors (22034644184).

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

21245136388 is a wasteful number, since it uses less digits than its factorization.

21245136388 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77092 (or 77083 counting only the distinct ones).

The product of its digits is 276480, while the sum is 43.

The spelling of 21245136388 in words is "twenty-one billion, two hundred forty-five million, one hundred thirty-six thousand, three hundred eighty-eight".