21887815680 has 416 divisors, whose sum is σ = 81244235520. Its totient is φ = 5579735040.

The previous prime is 21887815661. The next prime is 21887815717. The reversal of 21887815680 is 8651878812.

21887815680 is a `hidden beast` number, since 2 + 1 + 8 + 8 + 78 + 1 + 568 + 0 = 666.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 12717220 + ... + 12718940.

Almost surely, 2^21887815680 is an apocalyptic number.

21887815680 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 21887815680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40622117760).

21887815680 is an abundant number, since it is smaller than the sum of its proper divisors (59356419840).

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

21887815680 is a wasteful number, since it uses less digits than its factorization.

21887815680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1782 (or 1754 counting only the distinct ones).

The product of its (nonzero) digits is 1720320, while the sum is 54.

The spelling of 21887815680 in words is "twenty-one billion, eight hundred eighty-seven million, eight hundred fifteen thousand, six hundred eighty".