7820915778 has 48 divisors (see below), whose sum is σ = 18392564736. Its totient is φ = 2387478240.

The previous prime is 7820915749. The next prime is 7820915863. The reversal of 7820915778 is 8775190287.

It is a happy number.

It is a super-2 number, since 2×7820915778² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 101868 + ... + 161303.

It is an arithmetic number, because the mean of its divisors is an integer number (383178432).

Almost surely, 2^7820915778 is an apocalyptic number.

7820915778 is a gapful number since it is divisible by the number (78) formed by its first and last digit.

7820915778 is an abundant number, since it is smaller than the sum of its proper divisors (10571648958).

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

7820915778 is a wasteful number, since it uses less digits than its factorization.

7820915778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 263319 (or 263316 counting only the distinct ones).

The product of its (nonzero) digits is 1975680, while the sum is 54.

The square root of 7820915778 is about 88435.9416640090. The cubic root of 7820915778 is about 1984.9635507353.

The spelling of 7820915778 in words is "seven billion, eight hundred twenty million, nine hundred fifteen thousand, seven hundred seventy-eight".