7777638820 has 24 divisors (see below), whose sum is σ = 18666333504. Its totient is φ = 2666618976.

The previous prime is 7777638797. The next prime is 7777638821. The reversal of 7777638820 is 288367777.

It is a super-2 number, since 2×7777638820² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (7777638821) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27777142 + ... + 27777421.

It is an arithmetic number, because the mean of its divisors is an integer number (777763896).

Almost surely, 2^7777638820 is an apocalyptic number.

7777638820 is a gapful number since it is divisible by the number (70) formed by its first and last digit.

It is an amenable number.

7777638820 is an abundant number, since it is smaller than the sum of its proper divisors (10888694684).

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

7777638820 is a wasteful number, since it uses less digits than its factorization.

7777638820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55554579 (or 55554577 counting only the distinct ones).

The product of its (nonzero) digits is 5531904, while the sum is 55.

The square root of 7777638820 is about 88190.9225487521. The cubic root of 7777638820 is about 1981.2955181719.

The spelling of 7777638820 in words is "seven billion, seven hundred seventy-seven million, six hundred thirty-eight thousand, eight hundred twenty".