1261061531 has 4 divisors (see below), whose sum is σ = 1261976064. Its totient is φ = 1260147000.

The previous prime is 1261061519. The next prime is 1261061533. The reversal of 1261061531 is 1351601621.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1351601621 = 33349 ⋅40529.

It is a cyclic number.

It is not a de Polignac number, because 1261061531 - 2¹⁴ = 1261045147 is a prime.

It is a super-2 number, since 2×1261061531² = 3180552369936127922, which contains 22 as substring.

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 1261061531.

It is not an unprimeable number, because it can be changed into a prime (1261061533) 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, 455195 + ... + 457956.

It is an arithmetic number, because the mean of its divisors is an integer number (315494016).

Almost surely, 2^1261061531 is an apocalyptic number.

1261061531 is a deficient number, since it is larger than the sum of its proper divisors (914533).

1261061531 is an equidigital number, since it uses as much as digits as its factorization.

1261061531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 914532.

The product of its (nonzero) digits is 1080, while the sum is 26.

The square root of 1261061531 is about 35511.4281746032. The cubic root of 1261061531 is about 1080.3855307981.

The spelling of 1261061531 in words is "one billion, two hundred sixty-one million, sixty-one thousand, five hundred thirty-one".