1231201531 has 4 divisors (see below), whose sum is σ = 1407087472. Its totient is φ = 1055315592.

The previous prime is 1231201513. The next prime is 1231201541. The reversal of 1231201531 is 1351021321.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1231201531 - 2⁷ = 1231201403 is a prime.

It is a super-2 number, since 2×1231201531² = 3031714419873487922, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1231201499 and 1231201508.

It is not an unprimeable number, because it can be changed into a prime (1231201511) 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, 87942960 + ... + 87942973.

It is an arithmetic number, because the mean of its divisors is an integer number (351771868).

Almost surely, 2^1231201531 is an apocalyptic number.

1231201531 is a deficient number, since it is larger than the sum of its proper divisors (175885941).

1231201531 is an equidigital number, since it uses as much as digits as its factorization.

1231201531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 175885940.

The product of its (nonzero) digits is 180, while the sum is 19.

The square root of 1231201531 is about 35088.4814575952. The cubic root of 1231201531 is about 1071.7900368822.

Adding to 1231201531 its reverse (1351021321), we get a palindrome (2582222852).

The spelling of 1231201531 in words is "one billion, two hundred thirty-one million, two hundred one thousand, five hundred thirty-one".