21780766277 has 4 divisors (see below), whose sum is σ = 21781585056. Its totient is φ = 21779947500.

The previous prime is 21780766247. The next prime is 21780766291. The reversal of 21780766277 is 77266708712.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21780766277 - 2⁶ = 21780766213 is a prime.

It is a super-2 number, since 2×21780766277² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21780766237) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 368099 + ... + 423152.

It is an arithmetic number, because the mean of its divisors is an integer number (5445396264).

Almost surely, 2^21780766277 is an apocalyptic number.

It is an amenable number.

21780766277 is a deficient number, since it is larger than the sum of its proper divisors (818779).

21780766277 is an equidigital number, since it uses as much as digits as its factorization.

21780766277 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 818778.

The product of its (nonzero) digits is 2765952, while the sum is 53.

The spelling of 21780766277 in words is "twenty-one billion, seven hundred eighty million, seven hundred sixty-six thousand, two hundred seventy-seven".