158661997 has 4 divisors (see below), whose sum is σ = 170866780. Its totient is φ = 146457216.

The previous prime is 158661983. The next prime is 158662001. The reversal of 158661997 is 799166851.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 799166851 = 7 ⋅114166693.

It can be written as a sum of positive squares in 2 ways, for example, as 78039556 + 80622441 = 8834^2 + 8979^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-158661997 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 (158661977) 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, 6102372 + ... + 6102397.

It is an arithmetic number, because the mean of its divisors is an integer number (42716695).

Almost surely, 2^158661997 is an apocalyptic number.

It is an amenable number.

158661997 is a deficient number, since it is larger than the sum of its proper divisors (12204783).

158661997 is a wasteful number, since it uses less digits than its factorization.

158661997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12204782.

The product of its digits is 816480, while the sum is 52.

The square root of 158661997 is about 12596.1103917043. The cubic root of 158661997 is about 541.3659940885.

The spelling of 158661997 in words is "one hundred fifty-eight million, six hundred sixty-one thousand, nine hundred ninety-seven".