21286249788 has 12 divisors (see below), whose sum is σ = 49667916200. Its totient is φ = 7095416592.

The previous prime is 21286249781. The next prime is 21286249837. The reversal of 21286249788 is 88794268212.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21286249781) 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 3 ways as a sum of consecutive naturals, for example, 886927063 + ... + 886927086.

Almost surely, 2^21286249788 is an apocalyptic number.

It is an amenable number.

21286249788 is an abundant number, since it is smaller than the sum of its proper divisors (28381666412).

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

21286249788 is a wasteful number, since it uses less digits than its factorization.

21286249788 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1773854156 (or 1773854154 counting only the distinct ones).

The product of its digits is 6193152, while the sum is 57.

The spelling of 21286249788 in words is "twenty-one billion, two hundred eighty-six million, two hundred forty-nine thousand, seven hundred eighty-eight".