21021420 has 48 divisors (see below), whose sum is σ = 67269888. Its totient is φ = 4804800.

The previous prime is 21021419. The next prime is 21021431. The reversal of 21021420 is 2412012.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21021396 and 21021405.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24606 + ... + 25445.

It is an arithmetic number, because the mean of its divisors is an integer number (1401456).

Almost surely, 2^21021420 is an apocalyptic number.

21021420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21021420 is an abundant number, since it is smaller than the sum of its proper divisors (46248468).

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

21021420 is a wasteful number, since it uses less digits than its factorization.

21021420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50070 (or 50068 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 12.

The square root of 21021420 is about 4584.9122129000. The cubic root of 21021420 is about 275.9861891850.

Adding to 21021420 its reverse (2412012), we get a palindrome (23433432).

The spelling of 21021420 in words is "twenty-one million, twenty-one thousand, four hundred twenty".