201680929921 has 9 divisors (see below), whose sum is σ = 214250482249. Its totient is φ = 189810160384.

The previous prime is 201680929897. The next prime is 201680929927. The reversal of 201680929921 is 129929086102.

The square root of 201680929921 is 449089.

It is a perfect power (a square), and thus also a powerful number.

201680929921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 1227731521 + 200453198400 = 35039^2 + 447720^2 .

It is not a de Polignac number, because 201680929921 - 2⁵ = 201680929889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (201680929927) 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 8 ways as a sum of consecutive naturals, for example, 7621305 + ... + 7647721.

Almost surely, 2^201680929921 is an apocalyptic number.

201680929921 is the 449089-th square number.

201680929921 is the 224545-th centered octagonal number.

It is an amenable number.

201680929921 is a deficient number, since it is larger than the sum of its proper divisors (12569552328).

201680929921 is an frugal number, since it uses more digits than its factorization.

201680929921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52868 (or 26434 counting only the distinct ones).

The product of its (nonzero) digits is 279936, while the sum is 49.

Multiplying 201680929921 by its sum of digits (49), we get a square (9882365566129 = 3143623²).

The spelling of 201680929921 in words is "two hundred one billion, six hundred eighty million, nine hundred twenty-nine thousand, nine hundred twenty-one".