821404253 has 2 divisors, whose sum is σ = 821404254. Its totient is φ = 821404252.

The previous prime is 821404247. The next prime is 821404279. The reversal of 821404253 is 352404128.

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., 434180569 + 387223684 = 20837^2 + 19678^2 .

It is a cyclic number.

It is not a de Polignac number, because 821404253 - 2¹² = 821400157 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (821404153) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410702126 + 410702127.

It is an arithmetic number, because the mean of its divisors is an integer number (410702127).

Almost surely, 2^821404253 is an apocalyptic number.

It is an amenable number.

821404253 is a deficient number, since it is larger than the sum of its proper divisors (1).

821404253 is an equidigital number, since it uses as much as digits as its factorization.

821404253 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7680, while the sum is 29.

The square root of 821404253 is about 28660.1509591279. The cubic root of 821404253 is about 936.5241531354.

The spelling of 821404253 in words is "eight hundred twenty-one million, four hundred four thousand, two hundred fifty-three".