21421249686 has 64 divisors (see below), whose sum is σ = 52286860800. Its totient is φ = 6470484768.

The previous prime is 21421249673. The next prime is 21421249697. The reversal of 21421249686 is 68694212412.

It is a happy number.

21421249686 is a `hidden beast` number, since 2 + 142 + 12 + 496 + 8 + 6 = 666.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 430281 + ... + 477476.

It is an arithmetic number, because the mean of its divisors is an integer number (816982200).

Almost surely, 2^21421249686 is an apocalyptic number.

21421249686 is an abundant number, since it is smaller than the sum of its proper divisors (30865611114).

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

21421249686 is a wasteful number, since it uses less digits than its factorization.

21421249686 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 907810 (or 907804 counting only the distinct ones).

The product of its digits is 331776, while the sum is 45.

The spelling of 21421249686 in words is "twenty-one billion, four hundred twenty-one million, two hundred forty-nine thousand, six hundred eighty-six".