201651561 has 6 divisors (see below), whose sum is σ = 291274490. Its totient is φ = 134434368.

The previous prime is 201651547. The next prime is 201651581. The reversal of 201651561 is 165156102.

It is a happy number.

201651561 is a `hidden beast` number, since 2 + 0 + 1 + 651 + 5 + 6 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 124545600 + 77105961 = 11160^2 + 8781^2 .

It is not a de Polignac number, because 201651561 - 2¹⁴ = 201635177 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (201651581) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 11202856 + ... + 11202873.

Almost surely, 2^201651561 is an apocalyptic number.

It is an amenable number.

201651561 is a deficient number, since it is larger than the sum of its proper divisors (89622929).

201651561 is a wasteful number, since it uses less digits than its factorization.

201651561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22405735 (or 22405732 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 27.

The square root of 201651561 is about 14200.4070716300. The cubic root of 201651561 is about 586.4088681301.

The spelling of 201651561 in words is "two hundred one million, six hundred fifty-one thousand, five hundred sixty-one".