1247261665 has 16 divisors (see below), whose sum is σ = 1621177488. Its totient is φ = 915722496.

The previous prime is 1247261663. The next prime is 1247261671. The reversal of 1247261665 is 5661627421.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 889249 + 1246372416 = 943^2 + 35304^2 .

It is not a de Polignac number, because 1247261665 - 2¹ = 1247261663 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1247261663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 44214 + ... + 66703.

It is an arithmetic number, because the mean of its divisors is an integer number (101323593).

Almost surely, 2^1247261665 is an apocalyptic number.

It is an amenable number.

1247261665 is a deficient number, since it is larger than the sum of its proper divisors (373915823).

1247261665 is a wasteful number, since it uses less digits than its factorization.

1247261665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 111108.

The product of its digits is 120960, while the sum is 40.

The square root of 1247261665 is about 35316.5919222113. The cubic root of 1247261665 is about 1076.4301613942.

The spelling of 1247261665 in words is "one billion, two hundred forty-seven million, two hundred sixty-one thousand, six hundred sixty-five".