21851557848 has 96 divisors (see below), whose sum is σ = 62328052800. Its totient is φ = 6896954304.

The previous prime is 21851557837. The next prime is 21851557877. The reversal of 21851557848 is 84875515812.

It is a happy number.

21851557848 is a `hidden beast` number, since 2 + 1 + 8 + 5 + 1 + 557 + 84 + 8 = 666.

It is a super-2 number, since 2×21851557848² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21851557794 and 21851557803.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4379211 + ... + 4384197.

It is an arithmetic number, because the mean of its divisors is an integer number (649250550).

Almost surely, 2^21851557848 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 21851557848, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31164026400).

21851557848 is an abundant number, since it is smaller than the sum of its proper divisors (40476494952).

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

21851557848 is a wasteful number, since it uses less digits than its factorization.

21851557848 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8221 (or 8214 counting only the distinct ones).

The product of its digits is 3584000, while the sum is 54.

The spelling of 21851557848 in words is "twenty-one billion, eight hundred fifty-one million, five hundred fifty-seven thousand, eight hundred forty-eight".