21280778860 has 24 divisors (see below), whose sum is σ = 48752330256. Its totient is φ = 7738464960.

The previous prime is 21280778851. The next prime is 21280778861. The reversal of 21280778860 is 6887708212.

It is not an unprimeable number, because it can be changed into a prime (21280778861) 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, 48365187 + ... + 48365626.

It is an arithmetic number, because the mean of its divisors is an integer number (2031347094).

Almost surely, 2^21280778860 is an apocalyptic number.

21280778860 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21280778860 is an abundant number, since it is smaller than the sum of its proper divisors (27471551396).

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

21280778860 is a wasteful number, since it uses less digits than its factorization.

21280778860 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 96730833 (or 96730831 counting only the distinct ones).

The product of its (nonzero) digits is 602112, while the sum is 49.

The spelling of 21280778860 in words is "twenty-one billion, two hundred eighty million, seven hundred seventy-eight thousand, eight hundred sixty".