1231721266 has 16 divisors (see below), whose sum is σ = 1854404928. Its totient is φ = 613591600.

The previous prime is 1231721237. The next prime is 1231721269. The reversal of 1231721266 is 6621271321.

It is not an unprimeable number, because it can be changed into a prime (1231721269) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1160376 + ... + 1161436.

It is an arithmetic number, because the mean of its divisors is an integer number (115900308).

Almost surely, 2^1231721266 is an apocalyptic number.

1231721266 is a deficient number, since it is larger than the sum of its proper divisors (622683662).

1231721266 is a wasteful number, since it uses less digits than its factorization.

1231721266 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2657.

The product of its digits is 6048, while the sum is 31.

The square root of 1231721266 is about 35095.8867390468. The cubic root of 1231721266 is about 1071.9408295337.

Adding to 1231721266 its reverse (6621271321), we get a palindrome (7852992587).

The spelling of 1231721266 in words is "one billion, two hundred thirty-one million, seven hundred twenty-one thousand, two hundred sixty-six".