21278123240 has 32 divisors (see below), whose sum is σ = 52228121760. Its totient is φ = 7737499200.

The previous prime is 21278123221. The next prime is 21278123261. The reversal of 21278123240 is 4232187212.

It is a junction number, because it is equal to n+sod(n) for n = 21278123197 and 21278123206.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24179246 + ... + 24180125.

It is an arithmetic number, because the mean of its divisors is an integer number (1632128805).

Almost surely, 2^21278123240 is an apocalyptic number.

21278123240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21278123240 is an abundant number, since it is smaller than the sum of its proper divisors (30949998520).

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

21278123240 is a wasteful number, since it uses less digits than its factorization.

21278123240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48359393 (or 48359389 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 32.

The spelling of 21278123240 in words is "twenty-one billion, two hundred seventy-eight million, one hundred twenty-three thousand, two hundred forty".