21003980 has 24 divisors (see below), whose sum is σ = 44643312. Its totient is φ = 8299712.

The previous prime is 21003937. The next prime is 21004043. The reversal of 21003980 is 8930012.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4667 + ... + 7986.

It is an arithmetic number, because the mean of its divisors is an integer number (1860138).

Almost surely, 2^21003980 is an apocalyptic number.

21003980 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21003980 is an abundant number, since it is smaller than the sum of its proper divisors (23639332).

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

21003980 is a wasteful number, since it uses less digits than its factorization.

21003980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12745 (or 12743 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 21003980 is about 4583.0099279840. The cubic root of 21003980 is about 275.9098459311.

Adding to 21003980 its reverse (8930012), we get a palindrome (29933992).

The spelling of 21003980 in words is "twenty-one million, three thousand, nine hundred eighty".