216831821636 has 6 divisors (see below), whose sum is σ = 379455687870. Its totient is φ = 108415910816.

The previous prime is 216831821627. The next prime is 216831821659. The reversal of 216831821636 is 636128138612.

It can be written as a sum of positive squares in only one way, i.e., 196878564100 + 19953257536 = 443710^2 + 141256^2 .

It is a super-2 number, since 2×216831821636² (a number of 23 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27103977701 + ... + 27103977708.

It is an arithmetic number, because the mean of its divisors is an integer number (63242614645).

Almost surely, 2^216831821636 is an apocalyptic number.

It is an amenable number.

216831821636 is a deficient number, since it is larger than the sum of its proper divisors (162623866234).

216831821636 is a wasteful number, since it uses less digits than its factorization.

216831821636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54207955413 (or 54207955411 counting only the distinct ones).

The product of its digits is 497664, while the sum is 47.

The spelling of 216831821636 in words is "two hundred sixteen billion, eight hundred thirty-one million, eight hundred twenty-one thousand, six hundred thirty-six".