201661520 has 20 divisors (see below), whose sum is σ = 468863220. Its totient is φ = 80664576.

The previous prime is 201661511. The next prime is 201661553. The reversal of 201661520 is 25166102.

It can be written as a sum of positive squares in 2 ways, for example, as 85969984 + 115691536 = 9272^2 + 10756^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1260305 + ... + 1260464.

It is an arithmetic number, because the mean of its divisors is an integer number (23443161).

Almost surely, 2^201661520 is an apocalyptic number.

201661520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

201661520 is an abundant number, since it is smaller than the sum of its proper divisors (267201700).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

201661520 is a wasteful number, since it uses less digits than its factorization.

201661520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2520782 (or 2520776 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 201661520 is about 14200.7577262624. The cubic root of 201661520 is about 586.4185216628.

It can be divided in two parts, 2016 and 61520, that added together give a palindrome (63536).

The spelling of 201661520 in words is "two hundred one million, six hundred sixty-one thousand, five hundred twenty".