201557921 has 4 divisors (see below), whose sum is σ = 201603072. Its totient is φ = 201512772.

The previous prime is 201557911. The next prime is 201557957. The reversal of 201557921 is 129755102.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 129755102 = 2 ⋅64877551.

It is a cyclic number.

It is not a de Polignac number, because 201557921 - 2⁶ = 201557857 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (201557911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15041 + ... + 25086.

It is an arithmetic number, because the mean of its divisors is an integer number (50400768).

Almost surely, 2^201557921 is an apocalyptic number.

It is an amenable number.

201557921 is a deficient number, since it is larger than the sum of its proper divisors (45151).

201557921 is an equidigital number, since it uses as much as digits as its factorization.

201557921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45150.

The product of its (nonzero) digits is 6300, while the sum is 32.

The square root of 201557921 is about 14197.1096001968. The cubic root of 201557921 is about 586.3180847545.

The spelling of 201557921 in words is "two hundred one million, five hundred fifty-seven thousand, nine hundred twenty-one".