18877021 has 4 divisors (see below), whose sum is σ = 19987452. Its totient is φ = 17766592.

The previous prime is 18877007. The next prime is 18877031. The reversal of 18877021 is 12077881.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12077881 = 71 ⋅170111.

It can be written as a sum of positive squares in 2 ways, for example, as 16088121 + 2788900 = 4011^2 + 1670^2 .

It is a cyclic number.

It is not a de Polignac number, because 18877021 - 2¹⁷ = 18745949 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 (18877031) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 555190 + ... + 555223.

It is an arithmetic number, because the mean of its divisors is an integer number (4996863).

Almost surely, 2^18877021 is an apocalyptic number.

It is an amenable number.

18877021 is a deficient number, since it is larger than the sum of its proper divisors (1110431).

18877021 is a wasteful number, since it uses less digits than its factorization.

18877021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1110430.

The product of its (nonzero) digits is 6272, while the sum is 34.

The square root of 18877021 is about 4344.7693839835. The cubic root of 18877021 is about 266.2632035889.

The spelling of 18877021 in words is "eighteen million, eight hundred seventy-seven thousand, twenty-one".