21819781803636 has 36 divisors (see below), whose sum is σ = 55180062456064. Its totient is φ = 7270029450000.

The previous prime is 21819781803593. The next prime is 21819781803641. The reversal of 21819781803636 is 63630818791812.

21819781803636 is a `hidden beast` number, since 2 + 1 + 8 + 1 + 97 + 8 + 180 + 363 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×21819781803636² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 134549140 + ... + 134711211.

Almost surely, 2^{21819781803636} is an apocalyptic number.

It is an amenable number.

21819781803636 is an abundant number, since it is smaller than the sum of its proper divisors (33360280652428).

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

21819781803636 is a wasteful number, since it uses less digits than its factorization.

21819781803636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 269262612 (or 269262607 counting only the distinct ones).

The product of its (nonzero) digits is 20901888, while the sum is 63.

The spelling of 21819781803636 in words is "twenty-one trillion, eight hundred nineteen billion, seven hundred eighty-one million, eight hundred three thousand, six hundred thirty-six".