21649857278 has 12 divisors (see below), whose sum is σ = 37776791952. Its totient is φ = 9278510220.

The previous prime is 21649857263. The next prime is 21649857301. The reversal of 21649857278 is 87275894612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 110458358 + ... + 110458553.

It is an arithmetic number, because the mean of its divisors is an integer number (3148065996).

Almost surely, 2^21649857278 is an apocalyptic number.

21649857278 is a deficient number, since it is larger than the sum of its proper divisors (16126934674).

21649857278 is a wasteful number, since it uses less digits than its factorization.

21649857278 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 220916927 (or 220916920 counting only the distinct ones).

The product of its digits is 13547520, while the sum is 59.

The spelling of 21649857278 in words is "twenty-one billion, six hundred forty-nine million, eight hundred fifty-seven thousand, two hundred seventy-eight".