21377728161 has 12 divisors (see below), whose sum is σ = 30893935488. Its totient is φ = 14244898104.

The previous prime is 21377728129. The next prime is 21377728199. The reversal of 21377728161 is 16182777312.

It is not a de Polignac number, because 21377728161 - 2⁵ = 21377728129 is a prime.

It is a super-2 number, since 2×21377728161² (a number of 21 digits) contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21377728111) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 557125 + ... + 594258.

It is an arithmetic number, because the mean of its divisors is an integer number (2574494624).

Almost surely, 2^21377728161 is an apocalyptic number.

It is an amenable number.

21377728161 is a deficient number, since it is larger than the sum of its proper divisors (9516207327).

21377728161 is a wasteful number, since it uses less digits than its factorization.

21377728161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1153452 (or 1153449 counting only the distinct ones).

The product of its digits is 197568, while the sum is 45.

The spelling of 21377728161 in words is "twenty-one billion, three hundred seventy-seven million, seven hundred twenty-eight thousand, one hundred sixty-one".