21166095780 has 72 divisors (see below), whose sum is σ = 64240925112. Its totient is φ = 5641030656.

The previous prime is 21166095767. The next prime is 21166095787. The reversal of 21166095780 is 8759066112.

21166095780 is a `hidden beast` number, since 2 + 1 + 16 + 60 + 9 + 578 + 0 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 67371264 + 21098724516 = 8208^2 + 145254^2 .

It is a super-2 number, since 2×21166095780² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (21166095787) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 286774 + ... + 352946.

It is an arithmetic number, because the mean of its divisors is an integer number (892235071).

Almost surely, 2^21166095780 is an apocalyptic number.

21166095780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21166095780 is an abundant number, since it is smaller than the sum of its proper divisors (43074829332).

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

21166095780 is a wasteful number, since it uses less digits than its factorization.

21166095780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67965 (or 67960 counting only the distinct ones).

The product of its (nonzero) digits is 181440, while the sum is 45.

The spelling of 21166095780 in words is "twenty-one billion, one hundred sixty-six million, ninety-five thousand, seven hundred eighty".