21012620 has 12 divisors (see below), whose sum is σ = 44126544. Its totient is φ = 8405040.

The previous prime is 21012599. The next prime is 21012647. The reversal of 21012620 is 2621012.

It is a junction number, because it is equal to n+sod(n) for n = 21012595 and 21012604.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 525296 + ... + 525335.

It is an arithmetic number, because the mean of its divisors is an integer number (3677212).

Almost surely, 2^21012620 is an apocalyptic number.

21012620 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21012620 is an abundant number, since it is smaller than the sum of its proper divisors (23113924).

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

21012620 is a wasteful number, since it uses less digits than its factorization.

21012620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1050640 (or 1050638 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 21012620 is about 4583.9524430343. The cubic root of 21012620 is about 275.9476726395.

Adding to 21012620 its reverse (2621012), we get a palindrome (23633632).

The spelling of 21012620 in words is "twenty-one million, twelve thousand, six hundred twenty".