21351420 has 36 divisors (see below), whose sum is σ = 64766520. Its totient is φ = 5693664.

The previous prime is 21351413. The next prime is 21351433. The reversal of 21351420 is 2415312.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21351393 and 21351402.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 59130 + ... + 59489.

It is an arithmetic number, because the mean of its divisors is an integer number (1799070).

Almost surely, 2^21351420 is an apocalyptic number.

21351420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21351420 is an abundant number, since it is smaller than the sum of its proper divisors (43415100).

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

21351420 is a wasteful number, since it uses less digits than its factorization.

21351420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118634 (or 118629 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21351420 is about 4620.7596778019. The cubic root of 21351420 is about 277.4228663146.

Adding to 21351420 its reverse (2415312), we get a palindrome (23766732).

The spelling of 21351420 in words is "twenty-one million, three hundred fifty-one thousand, four hundred twenty".