781978158 has 128 divisors (see below), whose sum is σ = 1943222400. Its totient is φ = 231552000.

The previous prime is 781978157. The next prime is 781978187. The reversal of 781978158 is 851879187.

It is a super-2 number, since 2×781978158² = 1222979679178145928, which contains 22 as substring.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (781978157) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 2906848 + ... + 2907116.

It is an arithmetic number, because the mean of its divisors is an integer number (15181425).

Almost surely, 2^781978158 is an apocalyptic number.

781978158 is a gapful number since it is divisible by the number (78) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 781978158, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (971611200).

781978158 is an abundant number, since it is smaller than the sum of its proper divisors (1161244242).

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

781978158 is a wasteful number, since it uses less digits than its factorization.

781978158 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 435 (or 429 counting only the distinct ones).

The product of its digits is 1128960, while the sum is 54.

The square root of 781978158 is about 27963.8723713294. The cubic root of 781978158 is about 921.2939252223.

The spelling of 781978158 in words is "seven hundred eighty-one million, nine hundred seventy-eight thousand, one hundred fifty-eight".