1821688664 has 8 divisors (see below), whose sum is σ = 3415666260. Its totient is φ = 910844328.

The previous prime is 1821688663. The next prime is 1821688691. The reversal of 1821688664 is 4668861281.

It is a tau number, because it is divible by the number of its divisors (8).

It is a super-2 number, since 2×1821688664² = 6637099177092209792, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1821688663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 113855534 + ... + 113855549.

Almost surely, 2^1821688664 is an apocalyptic number.

It is an amenable number.

1821688664 is a deficient number, since it is larger than the sum of its proper divisors (1593977596).

1821688664 is a wasteful number, since it uses less digits than its factorization.

1821688664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 227711089 (or 227711085 counting only the distinct ones).

The product of its digits is 884736, while the sum is 50.

The square root of 1821688664 is about 42681.2448740662. The cubic root of 1821688664 is about 1221.3066409148.

The spelling of 1821688664 in words is "one billion, eight hundred twenty-one million, six hundred eighty-eight thousand, six hundred sixty-four".