21688003240 has 32 divisors (see below), whose sum is σ = 48842109000. Its totient is φ = 8667361024.

The previous prime is 21688003231. The next prime is 21688003291. The reversal of 21688003240 is 4230088612.

It can be written as a sum of positive squares in 4 ways, for example, as 11274617124 + 10413386116 = 106182^2 + 102046^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21688003196 and 21688003205.

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, 200095 + ... + 288814.

Almost surely, 2^21688003240 is an apocalyptic number.

21688003240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21688003240 is an abundant number, since it is smaller than the sum of its proper divisors (27154105760).

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

21688003240 is a wasteful number, since it uses less digits than its factorization.

21688003240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 490029 (or 490025 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 34.

The spelling of 21688003240 in words is "twenty-one billion, six hundred eighty-eight million, three thousand, two hundred forty".