166405620621 has 16 divisors (see below), whose sum is σ = 241605259200. Its totient is φ = 101474206848.

The previous prime is 166405620613. The next prime is 166405620631. The reversal of 166405620621 is 126026504661.

166405620621 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 166405620621 - 2³ = 166405620613 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 166405620621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166405620631) 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 15 ways as a sum of consecutive naturals, for example, 50332776 + ... + 50336081.

It is an arithmetic number, because the mean of its divisors is an integer number (15100328700).

Almost surely, 2^166405620621 is an apocalyptic number.

It is an amenable number.

166405620621 is a deficient number, since it is larger than the sum of its proper divisors (75199638579).

166405620621 is a wasteful number, since it uses less digits than its factorization.

166405620621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 100668908.

The product of its (nonzero) digits is 103680, while the sum is 39.

The spelling of 166405620621 in words is "one hundred sixty-six billion, four hundred five million, six hundred twenty thousand, six hundred twenty-one".