21777787108 has 48 divisors (see below), whose sum is σ = 47951164800. Its totient is φ = 8406996480.

The previous prime is 21777787063. The next prime is 21777787121. The reversal of 21777787108 is 80178777712.

It is a happy number.

It is a super-2 number, since 2×21777787108² (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 15 ways as a sum of consecutive naturals, for example, 290773 + ... + 357916.

It is an arithmetic number, because the mean of its divisors is an integer number (998982600).

Almost surely, 2^21777787108 is an apocalyptic number.

21777787108 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21777787108 is an abundant number, since it is smaller than the sum of its proper divisors (26173377692).

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

21777787108 is a wasteful number, since it uses less digits than its factorization.

21777787108 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 648820 (or 648818 counting only the distinct ones).

The product of its (nonzero) digits is 2151296, while the sum is 55.

The spelling of 21777787108 in words is "twenty-one billion, seven hundred seventy-seven million, seven hundred eighty-seven thousand, one hundred eight".