21291499845 has 288 divisors, whose sum is σ = 50398433280. Its totient is φ = 8196007680.

The previous prime is 21291499787. The next prime is 21291499847. The reversal of 21291499845 is 54899419212.

21291499845 is a `hidden beast` number, since 21 + 2 + 91 + 499 + 8 + 45 = 666.

It is not a de Polignac number, because 21291499845 - 2¹³ = 21291491653 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21291499791 and 21291499800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21291499847) by changing a digit.

It is a polite number, since it can be written in 287 ways as a sum of consecutive naturals, for example, 21659224 + ... + 21660206.

It is an arithmetic number, because the mean of its divisors is an integer number (174994560).

Almost surely, 2^21291499845 is an apocalyptic number.

It is an amenable number.

21291499845 is an abundant number, since it is smaller than the sum of its proper divisors (29106933435).

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

21291499845 is a wasteful number, since it uses less digits than its factorization.

21291499845 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1085 (or 1075 counting only the distinct ones).

The product of its digits is 1866240, while the sum is 54.

The spelling of 21291499845 in words is "twenty-one billion, two hundred ninety-one million, four hundred ninety-nine thousand, eight hundred forty-five".