18820457 has 4 divisors (see below), whose sum is σ = 19329156. Its totient is φ = 18311760.

The previous prime is 18820453. The next prime is 18820481. The reversal of 18820457 is 75402881.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 75402881 = 31 ⋅2432351.

It can be written as a sum of positive squares in 2 ways, for example, as 8904256 + 9916201 = 2984^2 + 3149^2 .

It is a cyclic number.

It is not a de Polignac number, because 18820457 - 2² = 18820453 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18820453) 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, 254294 + ... + 254367.

It is an arithmetic number, because the mean of its divisors is an integer number (4832289).

Almost surely, 2^18820457 is an apocalyptic number.

It is an amenable number.

18820457 is a deficient number, since it is larger than the sum of its proper divisors (508699).

18820457 is an equidigital number, since it uses as much as digits as its factorization.

18820457 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 508698.

The product of its (nonzero) digits is 17920, while the sum is 35.

The square root of 18820457 is about 4338.2550639629. The cubic root of 18820457 is about 265.9969896205.

The spelling of 18820457 in words is "eighteen million, eight hundred twenty thousand, four hundred fifty-seven".