201657790921 has 2 divisors, whose sum is σ = 201657790922. Its totient is φ = 201657790920.

The previous prime is 201657790913. The next prime is 201657791009. The reversal of 201657790921 is 129097756102.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 174526759696 + 27131031225 = 417764^2 + 164715^2 .

It is a cyclic number.

It is not a de Polignac number, because 201657790921 - 2³ = 201657790913 is a prime.

It is not a weakly prime, because it can be changed into another prime (201657790721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 100828895460 + 100828895461.

It is an arithmetic number, because the mean of its divisors is an integer number (100828895461).

Almost surely, 2^201657790921 is an apocalyptic number.

It is an amenable number.

201657790921 is a deficient number, since it is larger than the sum of its proper divisors (1).

201657790921 is an equidigital number, since it uses as much as digits as its factorization.

201657790921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 476280, while the sum is 49.

The spelling of 201657790921 in words is "two hundred one billion, six hundred fifty-seven million, seven hundred ninety thousand, nine hundred twenty-one".