1531523261 has 4 divisors (see below), whose sum is σ = 1531601532. Its totient is φ = 1531444992.

The previous prime is 1531523237. The next prime is 1531523311. The reversal of 1531523261 is 1623251351.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1623251351 = 293 ⋅5540107.

It can be written as a sum of positive squares in 2 ways, for example, as 787924900 + 743598361 = 28070^2 + 27269^2 .

It is a cyclic number.

It is not a de Polignac number, because 1531523261 - 2⁶ = 1531523197 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 (1531520261) 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, 19331 + ... + 58623.

It is an arithmetic number, because the mean of its divisors is an integer number (382900383).

Almost surely, 2^1531523261 is an apocalyptic number.

It is an amenable number.

1531523261 is a deficient number, since it is larger than the sum of its proper divisors (78271).

1531523261 is an equidigital number, since it uses as much as digits as its factorization.

1531523261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78270.

The product of its digits is 5400, while the sum is 29.

The square root of 1531523261 is about 39134.6810514664. The cubic root of 1531523261 is about 1152.6776323341.

The spelling of 1531523261 in words is "one billion, five hundred thirty-one million, five hundred twenty-three thousand, two hundred sixty-one".