821172113 has 4 divisors (see below), whose sum is σ = 847661568. Its totient is φ = 794682660.

The previous prime is 821172103. The next prime is 821172169. The reversal of 821172113 is 311271128.

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 821172113 - 2¹⁶ = 821106577 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (821172103) 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, 13244681 + ... + 13244742.

It is an arithmetic number, because the mean of its divisors is an integer number (211915392).

Almost surely, 2^821172113 is an apocalyptic number.

It is an amenable number.

821172113 is a deficient number, since it is larger than the sum of its proper divisors (26489455).

821172113 is a wasteful number, since it uses less digits than its factorization.

821172113 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26489454.

The product of its digits is 672, while the sum is 26.

The square root of 821172113 is about 28656.1007989573. The cubic root of 821172113 is about 936.4359200070.

The spelling of 821172113 in words is "eight hundred twenty-one million, one hundred seventy-two thousand, one hundred thirteen".