156821261 has 4 divisors (see below), whose sum is σ = 157506300. Its totient is φ = 156136224.

The previous prime is 156821257. The next prime is 156821263. The reversal of 156821261 is 162128651.

156821261 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 162128651 = 6961 ⋅23291.

It can be written as a sum of positive squares in 2 ways, for example, as 135606025 + 21215236 = 11645^2 + 4606^2 .

It is a cyclic number.

It is not a de Polignac number, because 156821261 - 2² = 156821257 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (156821263) 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, 342176 + ... + 342633.

It is an arithmetic number, because the mean of its divisors is an integer number (39376575).

Almost surely, 2^156821261 is an apocalyptic number.

It is an amenable number.

156821261 is a deficient number, since it is larger than the sum of its proper divisors (685039).

156821261 is an equidigital number, since it uses as much as digits as its factorization.

156821261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 685038.

The product of its digits is 5760, while the sum is 32.

The square root of 156821261 is about 12522.8295923885. The cubic root of 156821261 is about 539.2642712591.

The spelling of 156821261 in words is "one hundred fifty-six million, eight hundred twenty-one thousand, two hundred sixty-one".