21513020 has 12 divisors (see below), whose sum is σ = 45177384. Its totient is φ = 8605200.

The previous prime is 21513013. The next prime is 21513031. The reversal of 21513020 is 2031512.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21512986 and 21513004.

It is a congruent number.

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, 537806 + ... + 537845.

It is an arithmetic number, because the mean of its divisors is an integer number (3764782).

Almost surely, 2^21513020 is an apocalyptic number.

21513020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21513020 is an abundant number, since it is smaller than the sum of its proper divisors (23664364).

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

21513020 is a wasteful number, since it uses less digits than its factorization.

21513020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1075660 (or 1075658 counting only the distinct ones).

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

The square root of 21513020 is about 4638.2130179628. The cubic root of 21513020 is about 278.1210073071.

Adding to 21513020 its reverse (2031512), we get a palindrome (23544532).

The spelling of 21513020 in words is "twenty-one million, five hundred thirteen thousand, twenty".