21638314241778 has 64 divisors (see below), whose sum is σ = 47246994990720. Its totient is φ = 6566326414848.

The previous prime is 21638314241743. The next prime is 21638314241779. The reversal of 21638314241778 is 87714241383612.

It is not an unprimeable number, because it can be changed into a prime (21638314241779) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 97763625 + ... + 97984707.

It is an arithmetic number, because the mean of its divisors is an integer number (738234296730).

Almost surely, 2^{21638314241778} is an apocalyptic number.

21638314241778 is an abundant number, since it is smaller than the sum of its proper divisors (25608680748942).

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

21638314241778 is a wasteful number, since it uses less digits than its factorization.

21638314241778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 238363.

The product of its digits is 10838016, while the sum is 57.

The spelling of 21638314241778 in words is "twenty-one trillion, six hundred thirty-eight billion, three hundred fourteen million, two hundred forty-one thousand, seven hundred seventy-eight".