21203620 has 24 divisors (see below), whose sum is σ = 46872000. Its totient is φ = 8034912.

The previous prime is 21203603. The next prime is 21203621. The reversal of 21203620 is 2630212.

It is a super-2 number, since 2×21203620² = 899187002208800, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21203594 and 21203603.

It is not an unprimeable number, because it can be changed into a prime (21203621) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27520 + ... + 28279.

It is an arithmetic number, because the mean of its divisors is an integer number (1953000).

Almost surely, 2^21203620 is an apocalyptic number.

21203620 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21203620 is an abundant number, since it is smaller than the sum of its proper divisors (25668380).

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

21203620 is a wasteful number, since it uses less digits than its factorization.

21203620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55827 (or 55825 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 16.

The square root of 21203620 is about 4604.7388633885. The cubic root of 21203620 is about 276.7812528373.

Adding to 21203620 its reverse (2630212), we get a palindrome (23833832).

The spelling of 21203620 in words is "twenty-one million, two hundred three thousand, six hundred twenty".