1261253636 has 6 divisors (see below), whose sum is σ = 2207193870. Its totient is φ = 630626816.

The previous prime is 1261253633. The next prime is 1261253657. The reversal of 1261253636 is 6363521621.

It can be written as a sum of positive squares in only one way, i.e., 1260676036 + 577600 = 35506^2 + 760^2 .

It is a junction number, because it is equal to n+sod(n) for n = 1261253596 and 1261253605.

It is not an unprimeable number, because it can be changed into a prime (1261253633) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 157656701 + ... + 157656708.

It is an arithmetic number, because the mean of its divisors is an integer number (367865645).

Almost surely, 2^1261253636 is an apocalyptic number.

It is an amenable number.

1261253636 is a deficient number, since it is larger than the sum of its proper divisors (945940234).

1261253636 is a wasteful number, since it uses less digits than its factorization.

1261253636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 315313413 (or 315313411 counting only the distinct ones).

The product of its digits is 38880, while the sum is 35.

The square root of 1261253636 is about 35514.1329050844. The cubic root of 1261253636 is about 1080.4403885295.

The spelling of 1261253636 in words is "one billion, two hundred sixty-one million, two hundred fifty-three thousand, six hundred thirty-six".