70821 has 16 divisors (see below), whose sum is σ = 109120. Its totient is φ = 45360.

The previous prime is 70793. The next prime is 70823. The reversal of 70821 is 12807.

It is not a de Polignac number, because 70821 - 2⁹ = 70309 is a prime.

It is a super-2 number, since 2×70821² = 10031228082, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 70794 and 70803.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (70823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1131 + ... + 1191.

It is an arithmetic number, because the mean of its divisors is an integer number (6820).

2⁷⁰⁸²¹ is an apocalyptic number.

It is an amenable number.

70821 is a deficient number, since it is larger than the sum of its proper divisors (38299).

70821 is a wasteful number, since it uses less digits than its factorization.

70821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 113 (or 107 counting only the distinct ones).

The product of its (nonzero) digits is 112, while the sum is 18.

The square root of 70821 is about 266.1221524037. The cubic root of 70821 is about 41.3733497880.

It can be divided in two parts, 708 and 21, that added together give a 6-th power (729 = 3⁶).

The spelling of 70821 in words is "seventy thousand, eight hundred twenty-one".