158940821 has 4 divisors (see below), whose sum is σ = 171167052. Its totient is φ = 146714592.

The previous prime is 158940791. The next prime is 158940827. The reversal of 158940821 is 128049851.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 128049851 = 1231 ⋅104021.

It can be written as a sum of positive squares in 2 ways, for example, as 93508900 + 65431921 = 9670^2 + 8089^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-158940821 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (158940827) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6113096 + ... + 6113121.

It is an arithmetic number, because the mean of its divisors is an integer number (42791763).

Almost surely, 2^158940821 is an apocalyptic number.

It is an amenable number.

158940821 is a deficient number, since it is larger than the sum of its proper divisors (12226231).

158940821 is a wasteful number, since it uses less digits than its factorization.

158940821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12226230.

The product of its (nonzero) digits is 23040, while the sum is 38.

The square root of 158940821 is about 12607.1733945401. The cubic root of 158940821 is about 541.6829309304.

The spelling of 158940821 in words is "one hundred fifty-eight million, nine hundred forty thousand, eight hundred twenty-one".