21420666340 has 12 divisors (see below), whose sum is σ = 44983399356. Its totient is φ = 8568266528.

The previous prime is 21420666277. The next prime is 21420666389. The reversal of 21420666340 is 4366602412.

It can be written as a sum of positive squares in 2 ways, for example, as 8069788224 + 13350878116 = 89832^2 + 115546^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21420666296 and 21420666305.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 535516639 + ... + 535516678.

It is an arithmetic number, because the mean of its divisors is an integer number (3748616613).

Almost surely, 2^21420666340 is an apocalyptic number.

21420666340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21420666340 is an abundant number, since it is smaller than the sum of its proper divisors (23562733016).

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

21420666340 is a wasteful number, since it uses less digits than its factorization.

21420666340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1071033326 (or 1071033324 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 34.

The spelling of 21420666340 in words is "twenty-one billion, four hundred twenty million, six hundred sixty-six thousand, three hundred forty".