201661021 has 12 divisors (see below), whose sum is σ = 214850880. Its totient is φ = 189241280.

The previous prime is 201660971. The next prime is 201661027. The reversal of 201661021 is 120166102.

It is not a de Polignac number, because 201661021 - 2¹¹ = 201658973 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 201661021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (201661027) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 123750 + ... + 125368.

It is an arithmetic number, because the mean of its divisors is an integer number (17904240).

Almost surely, 2^201661021 is an apocalyptic number.

It is an amenable number.

201661021 is a deficient number, since it is larger than the sum of its proper divisors (13189859).

201661021 is a wasteful number, since it uses less digits than its factorization.

201661021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2084 (or 2067 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 19.

The square root of 201661021 is about 14200.7401567665. The cubic root of 201661021 is about 586.4180379759.

The spelling of 201661021 in words is "two hundred one million, six hundred sixty-one thousand, twenty-one".