21206231892 has 144 divisors (see below), whose sum is σ = 59100350400. Its totient is φ = 6629817600.

The previous prime is 21206231843. The next prime is 21206231927. The reversal of 21206231892 is 29813260212.

It is a happy number.

21206231892 is a `hidden beast` number, since 2 + 1 + 20 + 623 + 1 + 8 + 9 + 2 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1859584 + ... + 1870952.

It is an arithmetic number, because the mean of its divisors is an integer number (410419100).

Almost surely, 2^21206231892 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21206231892, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29550175200).

21206231892 is an abundant number, since it is smaller than the sum of its proper divisors (37894118508).

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

21206231892 is a wasteful number, since it uses less digits than its factorization.

21206231892 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11508 (or 11494 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The spelling of 21206231892 in words is "twenty-one billion, two hundred six million, two hundred thirty-one thousand, eight hundred ninety-two".