84421821 has 12 divisors (see below), whose sum is σ = 123726176. Its totient is φ = 51164520.

The previous prime is 84421817. The next prime is 84421837. The reversal of 84421821 is 12812448.

84421821 = 874² + 875² + ... + 972².

It is not a de Polignac number, because 84421821 - 2² = 84421817 is a prime.

It is a hoax number, since the sum of its digits (30) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (84421811) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 115921 + ... + 116646.

Almost surely, 2^84421821 is an apocalyptic number.

It is an amenable number.

84421821 is a deficient number, since it is larger than the sum of its proper divisors (39304355).

84421821 is a wasteful number, since it uses less digits than its factorization.

84421821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 232592 (or 232581 counting only the distinct ones).

The product of its digits is 4096, while the sum is 30.

The square root of 84421821 is about 9188.1347943965. The cubic root of 84421821 is about 438.6837748763.

The spelling of 84421821 in words is "eighty-four million, four hundred twenty-one thousand, eight hundred twenty-one".