158215681 has 4 divisors (see below), whose sum is σ = 170386132. Its totient is φ = 146045232.

The previous prime is 158215649. The next prime is 158215693. The reversal of 158215681 is 186512851.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 186512851 = 7 ⋅26644693.

It can be written as a sum of positive squares in 2 ways, for example, as 95726656 + 62489025 = 9784^2 + 7905^2 .

It is a cyclic number.

It is not a de Polignac number, because 158215681 - 2⁵ = 158215649 is a prime.

It is a super-4 number, since 4×158215681⁴ (a number of 34 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 158215681.

It is not an unprimeable number, because it can be changed into a prime (158210681) 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, 6085206 + ... + 6085231.

It is an arithmetic number, because the mean of its divisors is an integer number (42596533).

Almost surely, 2^158215681 is an apocalyptic number.

It is an amenable number.

158215681 is a deficient number, since it is larger than the sum of its proper divisors (12170451).

158215681 is a wasteful number, since it uses less digits than its factorization.

158215681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12170450.

The product of its digits is 19200, while the sum is 37.

The square root of 158215681 is about 12578.3814936581. The cubic root of 158215681 is about 540.8578967421.

The spelling of 158215681 in words is "one hundred fifty-eight million, two hundred fifteen thousand, six hundred eighty-one".