21718809778050 has 240 divisors, whose sum is σ = 75236716095552. Its totient is φ = 4512999369600.

The previous prime is 21718809778019. The next prime is 21718809778051. The reversal of 21718809778050 is 5087790881712.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is not an unprimeable number, because it can be changed into a prime (21718809778051) by changing a digit.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 34510677 + ... + 35134376.

Almost surely, 2^{21718809778050} is an apocalyptic number.

21718809778050 is an abundant number, since it is smaller than the sum of its proper divisors (53517906317502).

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

21718809778050 is a wasteful number, since it uses less digits than its factorization.

21718809778050 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69645095 (or 69645081 counting only the distinct ones).

The product of its (nonzero) digits is 15805440, while the sum is 63.

The spelling of 21718809778050 in words is "twenty-one trillion, seven hundred eighteen billion, eight hundred nine million, seven hundred seventy-eight thousand, fifty".