618719821 has 2 divisors, whose sum is σ = 618719822. Its totient is φ = 618719820.

The previous prime is 618719791. The next prime is 618719837. The reversal of 618719821 is 128917816.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 566678025 + 52041796 = 23805^2 + 7214^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-618719821 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (618719851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 309359910 + 309359911.

It is an arithmetic number, because the mean of its divisors is an integer number (309359911).

Almost surely, 2^618719821 is an apocalyptic number.

It is an amenable number.

618719821 is a deficient number, since it is larger than the sum of its proper divisors (1).

618719821 is an equidigital number, since it uses as much as digits as its factorization.

618719821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 48384, while the sum is 43.

The square root of 618719821 is about 24874.0792995439. The cubic root of 618719821 is about 852.1146062594.

The spelling of 618719821 in words is "six hundred eighteen million, seven hundred nineteen thousand, eight hundred twenty-one".