21086420 has 12 divisors (see below), whose sum is σ = 44281524. Its totient is φ = 8434560.

The previous prime is 21086413. The next prime is 21086431. The reversal of 21086420 is 2468012.

It can be written as a sum of positive squares in 2 ways, for example, as 5373124 + 15713296 = 2318^2 + 3964^2 .

It is a hoax number, since the sum of its digits (23) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 527141 + ... + 527180.

It is an arithmetic number, because the mean of its divisors is an integer number (3690127).

Almost surely, 2^21086420 is an apocalyptic number.

21086420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21086420 is an abundant number, since it is smaller than the sum of its proper divisors (23195104).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21086420 is a wasteful number, since it uses less digits than its factorization.

21086420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1054330 (or 1054328 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 23.

The square root of 21086420 is about 4591.9952090567. The cubic root of 21086420 is about 276.2703540076.

The spelling of 21086420 in words is "twenty-one million, eighty-six thousand, four hundred twenty".