21878154777420 has 36 divisors (see below), whose sum is σ = 66363736158720. Its totient is φ = 5834174607264.

The previous prime is 21878154777419. The next prime is 21878154777443. The reversal of 21878154777420 is 2477745187812.

It is a happy number.

21878154777420 is a `hidden beast` number, since 2 + 1 + 8 + 7 + 81 + 547 + 7 + 7 + 4 + 2 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 60772651980 + ... + 60772652339.

It is an arithmetic number, because the mean of its divisors is an integer number (1843437115520).

Almost surely, 2^{21878154777420} is an apocalyptic number.

21878154777420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21878154777420 is an abundant number, since it is smaller than the sum of its proper divisors (44485581381300).

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

21878154777420 is a wasteful number, since it uses less digits than its factorization.

21878154777420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 121545304334 (or 121545304329 counting only the distinct ones).

The product of its (nonzero) digits is 49172480, while the sum is 63.

The spelling of 21878154777420 in words is "twenty-one trillion, eight hundred seventy-eight billion, one hundred fifty-four million, seven hundred seventy-seven thousand, four hundred twenty".