821121253 has 4 divisors (see below), whose sum is σ = 829093408. Its totient is φ = 813149100.

The previous prime is 821121187. The next prime is 821121289. The reversal of 821121253 is 352121128.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 821121253 - 2¹³ = 821113061 is a prime.

It is a super-2 number, since 2×821121253² = 1348480224256580018, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821127253) 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, 3985923 + ... + 3986128.

It is an arithmetic number, because the mean of its divisors is an integer number (207273352).

Almost surely, 2^821121253 is an apocalyptic number.

It is an amenable number.

821121253 is a deficient number, since it is larger than the sum of its proper divisors (7972155).

821121253 is a wasteful number, since it uses less digits than its factorization.

821121253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7972154.

The product of its digits is 960, while the sum is 25.

The square root of 821121253 is about 28655.2133651104. The cubic root of 821121253 is about 936.4165866203.

The spelling of 821121253 in words is "eight hundred twenty-one million, one hundred twenty-one thousand, two hundred fifty-three".