20121784340 has 36 divisors (see below), whose sum is σ = 49154646996. Its totient is φ = 6898897152.

The previous prime is 20121784279. The next prime is 20121784343. The reversal of 20121784340 is 4348712102.

It can be written as a sum of positive squares in 2 ways, for example, as 9383021956 + 10738762384 = 96866^2 + 103628^2 .

It is a junction number, because it is equal to n+sod(n) for n = 20121784297 and 20121784306.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20121784343) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10265237 + ... + 10267196.

It is an arithmetic number, because the mean of its divisors is an integer number (1365406861).

Almost surely, 2^20121784340 is an apocalyptic number.

20121784340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20121784340 is an abundant number, since it is smaller than the sum of its proper divisors (29032862656).

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

20121784340 is a wasteful number, since it uses less digits than its factorization.

20121784340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20532456 (or 20532447 counting only the distinct ones).

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

The spelling of 20121784340 in words is "twenty billion, one hundred twenty-one million, seven hundred eighty-four thousand, three hundred forty".