1261438664 has 8 divisors (see below), whose sum is σ = 2365197510. Its totient is φ = 630719328.

The previous prime is 1261438621. The next prime is 1261438679. The reversal of 1261438664 is 4668341621.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 678602500 + 582836164 = 26050^2 + 24142^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 78839909 + ... + 78839924.

Almost surely, 2^1261438664 is an apocalyptic number.

It is an amenable number.

1261438664 is a deficient number, since it is larger than the sum of its proper divisors (1103758846).

1261438664 is a wasteful number, since it uses less digits than its factorization.

1261438664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 157679839 (or 157679835 counting only the distinct ones).

The product of its digits is 165888, while the sum is 41.

The square root of 1261438664 is about 35516.7378006483. The cubic root of 1261438664 is about 1080.4932200783.

The spelling of 1261438664 in words is "one billion, two hundred sixty-one million, four hundred thirty-eight thousand, six hundred sixty-four".