1261488639 has 8 divisors (see below), whose sum is σ = 1684031872. Its totient is φ = 839968920.

The previous prime is 1261488637. The next prime is 1261488643. The reversal of 1261488639 is 9368841621.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1261488639 - 2¹ = 1261488637 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 (1261488637) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 252997 + ... + 257934.

It is an arithmetic number, because the mean of its divisors is an integer number (210503984).

Almost surely, 2^1261488639 is an apocalyptic number.

1261488639 is a deficient number, since it is larger than the sum of its proper divisors (422543233).

1261488639 is an equidigital number, since it uses as much as digits as its factorization.

1261488639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 511757.

The product of its digits is 497664, while the sum is 48.

The square root of 1261488639 is about 35517.4413352088. The cubic root of 1261488639 is about 1080.5074886901.

The spelling of 1261488639 in words is "one billion, two hundred sixty-one million, four hundred eighty-eight thousand, six hundred thirty-nine".