1381287978 has 160 divisors (see below), whose sum is σ = 3779892864. Its totient is φ = 368022528.

The previous prime is 1381287937. The next prime is 1381287997. The reversal of 1381287978 is 8797821831.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 2640825 + ... + 2641347.

Almost surely, 2^1381287978 is an apocalyptic number.

1381287978 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 1381287978, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1889946432).

1381287978 is an abundant number, since it is smaller than the sum of its proper divisors (2398604886).

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

1381287978 is a wasteful number, since it uses less digits than its factorization.

1381287978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 698 (or 689 counting only the distinct ones).

The product of its digits is 1354752, while the sum is 54.

The square root of 1381287978 is about 37165.6828001316. The cubic root of 1381287978 is about 1113.6825391918.

The spelling of 1381287978 in words is "one billion, three hundred eighty-one million, two hundred eighty-seven thousand, nine hundred seventy-eight".