158171921 has 2 divisors, whose sum is σ = 158171922. Its totient is φ = 158171920.

The previous prime is 158171899. The next prime is 158171939. The reversal of 158171921 is 129171851.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 83539600 + 74632321 = 9140^2 + 8639^2 .

It is a cyclic number.

It is not a de Polignac number, because 158171921 - 2⁶ = 158171857 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (158171521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 79085960 + 79085961.

It is an arithmetic number, because the mean of its divisors is an integer number (79085961).

Almost surely, 2^158171921 is an apocalyptic number.

It is an amenable number.

158171921 is a deficient number, since it is larger than the sum of its proper divisors (1).

158171921 is an equidigital number, since it uses as much as digits as its factorization.

158171921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5040, while the sum is 35.

The square root of 158171921 is about 12576.6418808838. The cubic root of 158171921 is about 540.8080278462.

The spelling of 158171921 in words is "one hundred fifty-eight million, one hundred seventy-one thousand, nine hundred twenty-one".