18881487821 has 16 divisors (see below), whose sum is σ = 21792305664. Its totient is φ = 16024200624.

The previous prime is 18881487769. The next prime is 18881487829. The reversal of 18881487821 is 12878418881.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 18881487821 - 2¹⁸ = 18881225677 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18881487829) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1644326 + ... + 1655768.

It is an arithmetic number, because the mean of its divisors is an integer number (1362019104).

Almost surely, 2^18881487821 is an apocalyptic number.

It is an amenable number.

18881487821 is a deficient number, since it is larger than the sum of its proper divisors (2910817843).

18881487821 is a wasteful number, since it uses less digits than its factorization.

18881487821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13760.

The product of its digits is 1835008, while the sum is 56.

The spelling of 18881487821 in words is "eighteen billion, eight hundred eighty-one million, four hundred eighty-seven thousand, eight hundred twenty-one".