1261111251 has 16 divisors (see below), whose sum is σ = 1724129568. Its totient is φ = 819456000.

The previous prime is 1261111249. The next prime is 1261111303. The reversal of 1261111251 is 1521111621.

It is not a de Polignac number, because 1261111251 - 2¹ = 1261111249 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1261111211) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 143455 + ... + 151991.

It is an arithmetic number, because the mean of its divisors is an integer number (107758098).

Almost surely, 2^1261111251 is an apocalyptic number.

1261111251 is a deficient number, since it is larger than the sum of its proper divisors (463018317).

1261111251 is a wasteful number, since it uses less digits than its factorization.

1261111251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9782.

The product of its digits is 120, while the sum is 21.

The square root of 1261111251 is about 35512.1282240307. The cubic root of 1261111251 is about 1080.3997294345.

Adding to 1261111251 its reverse (1521111621), we get a palindrome (2782222872).

The spelling of 1261111251 in words is "one billion, two hundred sixty-one million, one hundred eleven thousand, two hundred fifty-one".