20166231156521 has 4 divisors (see below), whose sum is σ = 20195415283344. Its totient is φ = 20137047029700.

The previous prime is 20166231156509. The next prime is 20166231156587. The reversal of 20166231156521 is 12565113266102.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20166231156521 - 2³⁸ = 19891353249577 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20166231153521) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14592062375 + ... + 14592063756.

It is an arithmetic number, because the mean of its divisors is an integer number (5048853820836).

Almost surely, 2^{20166231156521} is an apocalyptic number.

It is an amenable number.

20166231156521 is a deficient number, since it is larger than the sum of its proper divisors (29184126823).

20166231156521 is an equidigital number, since it uses as much as digits as its factorization.

20166231156521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29184126822.

The product of its (nonzero) digits is 129600, while the sum is 41.

The spelling of 20166231156521 in words is "twenty trillion, one hundred sixty-six billion, two hundred thirty-one million, one hundred fifty-six thousand, five hundred twenty-one".