84000021 has 16 divisors (see below), whose sum is σ = 131123328. Its totient is φ = 46828800.

The previous prime is 84000017. The next prime is 84000023. The reversal of 84000021 is 12000048.

It is not a de Polignac number, because 84000021 - 2² = 84000017 is a prime.

It is a super-3 number, since 3×84000021³ (a number of 25 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (84000023) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 47920 + ... + 49641.

It is an arithmetic number, because the mean of its divisors is an integer number (8195208).

Almost surely, 2^84000021 is an apocalyptic number.

It is an amenable number.

84000021 is a deficient number, since it is larger than the sum of its proper divisors (47123307).

84000021 is a wasteful number, since it uses less digits than its factorization.

84000021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 97612.

The product of its (nonzero) digits is 64, while the sum is 15.

The square root of 84000021 is about 9165.1525355555. The cubic root of 84000021 is about 437.9519504848.

Adding to 84000021 its reverse (12000048), we get a palindrome (96000069).

It can be divided in two parts, 840000 and 21, that multiplied together give a square (17640000 = 4200²).

The spelling of 84000021 in words is "eighty-four million, twenty-one", and thus it is an aban number.