18746821 has 2 divisors, whose sum is σ = 18746822. Its totient is φ = 18746820.

The previous prime is 18746803. The next prime is 18746831. The reversal of 18746821 is 12864781.

18746821 is nontrivially palindromic in base 5.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10962721 + 7784100 = 3311^2 + 2790^2 .

It is a cyclic number.

It is not a de Polignac number, because 18746821 - 2¹⁵ = 18714053 is a prime.

It is a super-3 number, since 3×18746821³ (a number of 23 digits) contains 333 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18746831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9373410 + 9373411.

It is an arithmetic number, because the mean of its divisors is an integer number (9373411).

Almost surely, 2^18746821 is an apocalyptic number.

It is an amenable number.

18746821 is a deficient number, since it is larger than the sum of its proper divisors (1).

18746821 is an equidigital number, since it uses as much as digits as its factorization.

18746821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 21504, while the sum is 37.

The square root of 18746821 is about 4329.7599240605. The cubic root of 18746821 is about 265.6496272622.

It can be divided in two parts, 187468 and 21, that added together give a square (187489 = 433²).

The spelling of 18746821 in words is "eighteen million, seven hundred forty-six thousand, eight hundred twenty-one".