201856661 has 2 divisors, whose sum is σ = 201856662. Its totient is φ = 201856660.

The previous prime is 201856643. The next prime is 201856673. The reversal of 201856661 is 166658102.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 201810436 + 46225 = 14206^2 + 215^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-201856661 is a prime.

It is a super-2 number, since 2×201856661² = 81492223180137842, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (201856601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 100928330 + 100928331.

It is an arithmetic number, because the mean of its divisors is an integer number (100928331).

Almost surely, 2^201856661 is an apocalyptic number.

It is an amenable number.

201856661 is a deficient number, since it is larger than the sum of its proper divisors (1).

201856661 is an equidigital number, since it uses as much as digits as its factorization.

201856661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 17280, while the sum is 35.

The square root of 201856661 is about 14207.6268602466. The cubic root of 201856661 is about 586.6076131086.

The spelling of 201856661 in words is "two hundred one million, eight hundred fifty-six thousand, six hundred sixty-one".