1291899940 has 24 divisors (see below), whose sum is σ = 2714104512. Its totient is φ = 516547680.

The previous prime is 1291899929. The next prime is 1291899943. The reversal of 1291899940 is 499981921.

It is not an unprimeable number, because it can be changed into a prime (1291899943) 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, 42307 + ... + 66133.

It is an arithmetic number, because the mean of its divisors is an integer number (113087688).

Almost surely, 2^1291899940 is an apocalyptic number.

1291899940 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1291899940 is an abundant number, since it is smaller than the sum of its proper divisors (1422204572).

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

1291899940 is a wasteful number, since it uses less digits than its factorization.

1291899940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26547 (or 26545 counting only the distinct ones).

The product of its (nonzero) digits is 419904, while the sum is 52.

The square root of 1291899940 is about 35943.0096124406. The cubic root of 1291899940 is about 1089.1214029285.

It can be divided in two parts, 129189 and 9940, that added together give a square (139129 = 373²).

The spelling of 1291899940 in words is "one billion, two hundred ninety-one million, eight hundred ninety-nine thousand, nine hundred forty".