1278398499840 has 1056 divisors, whose sum is σ = 5568087343104. Its totient is φ = 263456686080.

The previous prime is 1278398499823. The next prime is 1278398499857. The reversal of 1278398499840 is 489948938721.

1278398499840 is a `hidden beast` number, since 1 + 2 + 7 + 8 + 3 + 98 + 499 + 8 + 40 = 666.

It is an interprime number because it is at equal distance from previous prime (1278398499823) and next prime (1278398499857).

It is a tau number, because it is divible by the number of its divisors (1056).

It is a Harshad number since it is a multiple of its sum of digits (72).

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 450614902 + ... + 450617738.

It is an arithmetic number, because the mean of its divisors is an integer number (5272809984).

Almost surely, 2^{1278398499840} is an apocalyptic number.

1278398499840 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 1278398499840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2784043671552).

1278398499840 is an abundant number, since it is smaller than the sum of its proper divisors (4289688843264).

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

1278398499840 is a wasteful number, since it uses less digits than its factorization.

1278398499840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3013 (or 2992 counting only the distinct ones).

The product of its (nonzero) digits is 250822656, while the sum is 72.

The spelling of 1278398499840 in words is "one trillion, two hundred seventy-eight billion, three hundred ninety-eight million, four hundred ninety-nine thousand, eight hundred forty".