21685710278 has 16 divisors (see below), whose sum is σ = 32633462736. Its totient is φ = 10807929600.

The previous prime is 21685710247. The next prime is 21685710281. The reversal of 21685710278 is 87201758612.

It is a super-2 number, since 2×21685710278² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

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, 1180250 + ... + 1198482.

It is an arithmetic number, because the mean of its divisors is an integer number (2039591421).

Almost surely, 2^21685710278 is an apocalyptic number.

21685710278 is a deficient number, since it is larger than the sum of its proper divisors (10947752458).

21685710278 is a wasteful number, since it uses less digits than its factorization.

21685710278 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20119.

The product of its (nonzero) digits is 376320, while the sum is 47.

The spelling of 21685710278 in words is "twenty-one billion, six hundred eighty-five million, seven hundred ten thousand, two hundred seventy-eight".