21452420 has 24 divisors (see below), whose sum is σ = 49146048. Its totient is φ = 7800800.

The previous prime is 21452413. The next prime is 21452443. The reversal of 21452420 is 2425412.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 21452392 and 21452401.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 48536 + ... + 48975.

It is an arithmetic number, because the mean of its divisors is an integer number (2047752).

Almost surely, 2^21452420 is an apocalyptic number.

21452420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21452420 is an abundant number, since it is smaller than the sum of its proper divisors (27693628).

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

21452420 is a wasteful number, since it uses less digits than its factorization.

21452420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97531 (or 97529 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 20.

The square root of 21452420 is about 4631.6757226732. The cubic root of 21452420 is about 277.8596154721.

Adding to 21452420 its reverse (2425412), we get a palindrome (23877832).

The spelling of 21452420 in words is "twenty-one million, four hundred fifty-two thousand, four hundred twenty".