21351020 has 12 divisors (see below), whose sum is σ = 44837184. Its totient is φ = 8540400.

The previous prime is 21351017. The next prime is 21351053. The reversal of 21351020 is 2015312.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21350986 and 21351004.

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, 533756 + ... + 533795.

It is an arithmetic number, because the mean of its divisors is an integer number (3736432).

Almost surely, 2^21351020 is an apocalyptic number.

21351020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21351020 is an abundant number, since it is smaller than the sum of its proper divisors (23486164).

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

21351020 is a wasteful number, since it uses less digits than its factorization.

21351020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1067560 (or 1067558 counting only the distinct ones).

The product of its (nonzero) digits is 60, while the sum is 14.

The square root of 21351020 is about 4620.7163946730. The cubic root of 21351020 is about 277.4211338796.

Adding to 21351020 its reverse (2015312), we get a palindrome (23366332).

The spelling of 21351020 in words is "twenty-one million, three hundred fifty-one thousand, twenty".