21780766278 has 24 divisors (see below), whose sum is σ = 47220552288. Its totient is φ = 7255810512.

The previous prime is 21780766247. The next prime is 21780766291. The reversal of 21780766278 is 87266708712.

It is a happy number.

21780766278 is a `hidden beast` number, since 2 + 1 + 7 + 8 + 0 + 7 + 6 + 627 + 8 = 666.

It is a congruent number.

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, 340126 + ... + 399057.

It is an arithmetic number, because the mean of its divisors is an integer number (1967523012).

Almost surely, 2^21780766278 is an apocalyptic number.

21780766278 is an abundant number, since it is smaller than the sum of its proper divisors (25439786010).

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

21780766278 is a wasteful number, since it uses less digits than its factorization.

21780766278 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 740828 (or 740825 counting only the distinct ones).

The product of its (nonzero) digits is 3161088, while the sum is 54.

The spelling of 21780766278 in words is "twenty-one billion, seven hundred eighty million, seven hundred sixty-six thousand, two hundred seventy-eight".