21103020 has 36 divisors (see below), whose sum is σ = 64013040. Its totient is φ = 5627424.

The previous prime is 21103003. The next prime is 21103021. The reversal of 21103020 is 2030112.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 21102993 and 21103011.

It is not an unprimeable number, because it can be changed into a prime (21103021) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 58440 + ... + 58799.

It is an arithmetic number, because the mean of its divisors is an integer number (1778140).

Almost surely, 2^21103020 is an apocalyptic number.

21103020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21103020 is an abundant number, since it is smaller than the sum of its proper divisors (42910020).

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

21103020 is a wasteful number, since it uses less digits than its factorization.

21103020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 117254 (or 117249 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 9.

The square root of 21103020 is about 4593.8023466405. The cubic root of 21103020 is about 276.3428316964.

Adding to 21103020 its reverse (2030112), we get a palindrome (23133132).

It can be divided in two parts, 21 and 103020, that added together give a square (103041 = 321²).

The spelling of 21103020 in words is "twenty-one million, one hundred three thousand, twenty".