821252921 has 2 divisors, whose sum is σ = 821252922. Its totient is φ = 821252920.

The previous prime is 821252909. The next prime is 821252951. The reversal of 821252921 is 129252128.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 749664400 + 71588521 = 27380^2 + 8461^2 .

It is a cyclic number.

It is not a de Polignac number, because 821252921 - 2⁶ = 821252857 is a prime.

It is a Chen prime.

It is equal to p_42182609 and since 821252921 and 42182609 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (821252951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410626460 + 410626461.

It is an arithmetic number, because the mean of its divisors is an integer number (410626461).

Almost surely, 2^821252921 is an apocalyptic number.

It is an amenable number.

821252921 is a deficient number, since it is larger than the sum of its proper divisors (1).

821252921 is an equidigital number, since it uses as much as digits as its factorization.

821252921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5760, while the sum is 32.

The square root of 821252921 is about 28657.5107258115. The cubic root of 821252921 is about 936.4666358706.

The spelling of 821252921 in words is "eight hundred twenty-one million, two hundred fifty-two thousand, nine hundred twenty-one".