21780655272 has 128 divisors (see below), whose sum is σ = 64416643200. Its totient is φ = 6795187200.

The previous prime is 21780655243. The next prime is 21780655279. The reversal of 21780655272 is 27255608712.

21780655272 is a `hidden beast` number, since 2 + 17 + 80 + 6 + 552 + 7 + 2 = 666.

It is not an unprimeable number, because it can be changed into a prime (21780655279) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 648247 + ... + 681017.

It is an arithmetic number, because the mean of its divisors is an integer number (503255025).

Almost surely, 2^21780655272 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 21780655272, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32208321600).

21780655272 is an abundant number, since it is smaller than the sum of its proper divisors (42635987928).

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

21780655272 is a wasteful number, since it uses less digits than its factorization.

21780655272 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32984 (or 32974 counting only the distinct ones).

The product of its (nonzero) digits is 470400, while the sum is 45.

The spelling of 21780655272 in words is "twenty-one billion, seven hundred eighty million, six hundred fifty-five thousand, two hundred seventy-two".