1261212640 has 48 divisors (see below), whose sum is σ = 2989895328. Its totient is φ = 502744576.

The previous prime is 1261212517. The next prime is 1261212671. The reversal of 1261212640 is 462121621.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33429 + ... + 60331.

It is an arithmetic number, because the mean of its divisors is an integer number (62289486).

Almost surely, 2^1261212640 is an apocalyptic number.

1261212640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1261212640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1494947664).

1261212640 is an abundant number, since it is smaller than the sum of its proper divisors (1728682688).

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

1261212640 is a wasteful number, since it uses less digits than its factorization.

1261212640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27211 (or 27203 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 25.

The square root of 1261212640 is about 35513.5557217241. Note that the first 3 decimals coincide. The cubic root of 1261212640 is about 1080.4286821307.

It can be divided in two parts, 12612 and 12640, that added together give a palindrome (25252).

The spelling of 1261212640 in words is "one billion, two hundred sixty-one million, two hundred twelve thousand, six hundred forty".