21166012761021 has 24 divisors (see below), whose sum is σ = 31226816784384. Its totient is φ = 13809034815840.

The previous prime is 21166012761011. The next prime is 21166012761109. The reversal of 21166012761021 is 12016721066112.

21166012761021 is a `hidden beast` number, since 2 + 1 + 1 + 6 + 6 + 0 + 12 + 7 + 610 + 21 = 666.

It is not a de Polignac number, because 21166012761021 - 2³⁰ = 21164939019197 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21166012761011) 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, 1586295 + ... + 6696891.

It is an arithmetic number, because the mean of its divisors is an integer number (1301117366016).

Almost surely, 2^{21166012761021} is an apocalyptic number.

It is an amenable number.

21166012761021 is a deficient number, since it is larger than the sum of its proper divisors (10060804023363).

21166012761021 is a wasteful number, since it uses less digits than its factorization.

21166012761021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5120441 (or 5120438 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 36.

The spelling of 21166012761021 in words is "twenty-one trillion, one hundred sixty-six billion, twelve million, seven hundred sixty-one thousand, twenty-one".