1291406640 has 80 divisors (see below), whose sum is σ = 4028977248. Its totient is φ = 342171648.

The previous prime is 1291406629. The next prime is 1291406681. The reversal of 1291406640 is 466041921.

1291406640 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (80).

It is a super-2 number, since 2×1291406640² = 3335462219672179200, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20544 + ... + 54816.

Almost surely, 2^1291406640 is an apocalyptic number.

1291406640 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 1291406640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2014488624).

1291406640 is an abundant number, since it is smaller than the sum of its proper divisors (2737570608).

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

1291406640 is a wasteful number, since it uses less digits than its factorization.

1291406640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34446 (or 34440 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 33.

The square root of 1291406640 is about 35936.1467049543. The cubic root of 1291406640 is about 1088.9827616480.

The spelling of 1291406640 in words is "one billion, two hundred ninety-one million, four hundred six thousand, six hundred forty".