821948513 has 2 divisors, whose sum is σ = 821948514. Its totient is φ = 821948512.

The previous prime is 821948509. The next prime is 821948551. The reversal of 821948513 is 315849128.

821948513 = 20272² + 20273².

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 410994529 + 410953984 = 20273^2 + 20272^2 .

It is a cyclic number.

It is not a de Polignac number, because 821948513 - 2² = 821948509 is a prime.

It is a super-2 number, since 2×821948513² = 1351198716045822338, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (821948713) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410974256 + 410974257.

It is an arithmetic number, because the mean of its divisors is an integer number (410974257).

Almost surely, 2^821948513 is an apocalyptic number.

821948513 is the 20273-rd centered square number.

It is an amenable number.

821948513 is a deficient number, since it is larger than the sum of its proper divisors (1).

821948513 is an equidigital number, since it uses as much as digits as its factorization.

821948513 is an evil number, because the sum of its binary digits is even.

The product of its digits is 69120, while the sum is 41.

The square root of 821948513 is about 28669.6444519286. The cubic root of 821948513 is about 936.7309535008.

The spelling of 821948513 in words is "eight hundred twenty-one million, nine hundred forty-eight thousand, five hundred thirteen".