21164977680 has 240 divisors, whose sum is σ = 83262510144. Its totient is φ = 4397890560.

The previous prime is 21164977643. The next prime is 21164977697. The reversal of 21164977680 is 8677946112.

It is a tau number, because it is divible by the number of its divisors (240).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 47554 + ... + 211166.

Almost surely, 2^21164977680 is an apocalyptic number.

21164977680 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 21164977680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41631255072).

21164977680 is an abundant number, since it is smaller than the sum of its proper divisors (62097532464).

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

21164977680 is a wasteful number, since it uses less digits than its factorization.

21164977680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 163654 (or 163641 counting only the distinct ones).

The product of its (nonzero) digits is 1016064, while the sum is 51.

The spelling of 21164977680 in words is "twenty-one billion, one hundred sixty-four million, nine hundred seventy-seven thousand, six hundred eighty".