1291390040 has 64 divisors (see below), whose sum is σ = 3107172960. Its totient is φ = 481331200.

The previous prime is 1291390019. The next prime is 1291390049. The reversal of 1291390040 is 400931921.

It is a happy number.

It is a super-2 number, since 2×1291390040² = 3335376470822403200, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1291389985 and 1291390012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1291390049) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 59279 + ... + 78081.

Almost surely, 2^1291390040 is an apocalyptic number.

1291390040 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 1291390040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1553586480).

1291390040 is an abundant number, since it is smaller than the sum of its proper divisors (1815782920).

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

1291390040 is a wasteful number, since it uses less digits than its factorization.

1291390040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18932 (or 18928 counting only the distinct ones).

The product of its (nonzero) digits is 1944, while the sum is 29.

The square root of 1291390040 is about 35935.9157389929. The cubic root of 1291390040 is about 1088.9780956271.

The spelling of 1291390040 in words is "one billion, two hundred ninety-one million, three hundred ninety thousand, forty".