1243726551 has 6 divisors (see below), whose sum is σ = 1796493920. Its totient is φ = 829151028.

The previous prime is 1243726507. The next prime is 1243726553. The reversal of 1243726551 is 1556273421.

It is a de Polignac number, because none of the positive numbers 2^k-1243726551 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1243726553) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 69095911 + ... + 69095928.

Almost surely, 2^1243726551 is an apocalyptic number.

1243726551 is a deficient number, since it is larger than the sum of its proper divisors (552767369).

1243726551 is a wasteful number, since it uses less digits than its factorization.

1243726551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 138191845 (or 138191842 counting only the distinct ones).

The product of its digits is 50400, while the sum is 36.

The square root of 1243726551 is about 35266.5074964902. The cubic root of 1243726551 is about 1075.4122236628.

Adding to 1243726551 its reverse (1556273421), we get a palindrome (2799999972).

The spelling of 1243726551 in words is "one billion, two hundred forty-three million, seven hundred twenty-six thousand, five hundred fifty-one".