21806351952 has 160 divisors (see below), whose sum is σ = 71867304960. Its totient is φ = 5532226560.

The previous prime is 21806351947. The next prime is 21806351969. The reversal of 21806351952 is 25915360812.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 90324 + ... + 227532.

It is an arithmetic number, because the mean of its divisors is an integer number (449170656).

Almost surely, 2^21806351952 is an apocalyptic number.

21806351952 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21806351952, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35933652480).

21806351952 is an abundant number, since it is smaller than the sum of its proper divisors (50060953008).

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

21806351952 is a wasteful number, since it uses less digits than its factorization.

21806351952 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 137281 (or 137275 counting only the distinct ones).

The product of its (nonzero) digits is 129600, while the sum is 42.

The spelling of 21806351952 in words is "twenty-one billion, eight hundred six million, three hundred fifty-one thousand, nine hundred fifty-two".