136020821 has 4 divisors (see below), whose sum is σ = 139338444. Its totient is φ = 132703200.

The previous prime is 136020799. The next prime is 136020823. The reversal of 136020821 is 128020631.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 128020631 = 101 ⋅1267531.

It can be written as a sum of positive squares in 2 ways, for example, as 36300625 + 99720196 = 6025^2 + 9986^2 .

It is a cyclic number.

It is not a de Polignac number, because 136020821 - 2¹⁸ = 135758677 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 (136020823) 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, 1658750 + ... + 1658831.

It is an arithmetic number, because the mean of its divisors is an integer number (34834611).

Almost surely, 2^136020821 is an apocalyptic number.

It is an amenable number.

136020821 is a deficient number, since it is larger than the sum of its proper divisors (3317623).

136020821 is an equidigital number, since it uses as much as digits as its factorization.

136020821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3317622.

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 136020821 is about 11662.7964485367. The cubic root of 136020821 is about 514.2825602504.

The spelling of 136020821 in words is "one hundred thirty-six million, twenty thousand, eight hundred twenty-one".