1291287771648 has 320 divisors, whose sum is σ = 4486420350720. Its totient is φ = 358967033856.

The previous prime is 1291287771637. The next prime is 1291287771667. The reversal of 1291287771648 is 8461777821921.

1291287771648 is a `hidden beast` number, since 1 + 291 + 287 + 7 + 7 + 1 + 64 + 8 = 666.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a nude number because it is divisible by every one of its digits.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3400090 + ... + 3760742.

It is an arithmetic number, because the mean of its divisors is an integer number (14020063596).

Almost surely, 2^{1291287771648} is an apocalyptic number.

1291287771648 is a gapful number since it is divisible by the number (18) 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 1291287771648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2243210175360).

1291287771648 is an abundant number, since it is smaller than the sum of its proper divisors (3195132579072).

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

1291287771648 is an equidigital number, since it uses as much as digits as its factorization.

1291287771648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 360724 (or 360702 counting only the distinct ones).

The product of its digits is 18966528, while the sum is 63.

The spelling of 1291287771648 in words is "one trillion, two hundred ninety-one billion, two hundred eighty-seven million, seven hundred seventy-one thousand, six hundred forty-eight".