821373021 has 32 divisors (see below), whose sum is σ = 1463884800. Its totient is φ = 444651120.

The previous prime is 821372977. The next prime is 821373031. The reversal of 821373021 is 120373128.

821373021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 821373021 - 2¹⁴ = 821356637 is a prime.

It is a super-4 number, since 4×821373021⁴ (a number of 37 digits) contains 4444 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821373031) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 110775 + ... + 117956.

It is an arithmetic number, because the mean of its divisors is an integer number (45746400).

Almost surely, 2^821373021 is an apocalyptic number.

It is an amenable number.

821373021 is a deficient number, since it is larger than the sum of its proper divisors (642511779).

821373021 is a wasteful number, since it uses less digits than its factorization.

821373021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 228766 (or 228760 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 821373021 is about 28659.6060859182. The cubic root of 821373021 is about 936.5122832621.

It can be divided in two parts, 82137 and 3021, that added together give a palindrome (85158).

The spelling of 821373021 in words is "eight hundred twenty-one million, three hundred seventy-three thousand, twenty-one".