21945874860 has 384 divisors, whose sum is σ = 84495882240. Its totient is φ = 4604802048.

The previous prime is 21945874837. The next prime is 21945874891. The reversal of 21945874860 is 6847854912.

It is a happy number.

21945874860 is a `hidden beast` number, since 2 + 19 + 4 + 587 + 48 + 6 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a junction number, because it is equal to n+sod(n) for n = 21945874797 and 21945874806.

It is an unprimeable number.

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 127 ways as a sum of consecutive naturals, for example, 9679447 + ... + 9681713.

It is an arithmetic number, because the mean of its divisors is an integer number (220041360).

Almost surely, 2^21945874860 is an apocalyptic number.

21945874860 is a gapful number since it is divisible by the number (20) 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 21945874860, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42247941120).

21945874860 is an abundant number, since it is smaller than the sum of its proper divisors (62550007380).

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

21945874860 is a wasteful number, since it uses less digits than its factorization.

21945874860 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2502 (or 2494 counting only the distinct ones).

The product of its (nonzero) digits is 3870720, while the sum is 54.

The spelling of 21945874860 in words is "twenty-one billion, nine hundred forty-five million, eight hundred seventy-four thousand, eight hundred sixty".