1261517380 has 24 divisors (see below), whose sum is σ = 2685479832. Its totient is φ = 497693952.

The previous prime is 1261517353. The next prime is 1261517381. The reversal of 1261517380 is 837151621.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 233417284 + 1028100096 = 15278^2 + 32064^2 .

It is a super-2 number, since 2×1261517380² = 3182852200084128800, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1261517381) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 430567 + ... + 433486.

It is an arithmetic number, because the mean of its divisors is an integer number (111894993).

Almost surely, 2^1261517380 is an apocalyptic number.

1261517380 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1261517380 is an abundant number, since it is smaller than the sum of its proper divisors (1423962452).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1261517380 is a wasteful number, since it uses less digits than its factorization.

1261517380 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 864135 (or 864133 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 34.

The square root of 1261517380 is about 35517.8459369371. The cubic root of 1261517380 is about 1080.5156945058.

The spelling of 1261517380 in words is "one billion, two hundred sixty-one million, five hundred seventeen thousand, three hundred eighty".