21601020 has 48 divisors (see below), whose sum is σ = 69124608. Its totient is φ = 4937280.

The previous prime is 21600991. The next prime is 21601061. The reversal of 21601020 is 2010612.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21600987 and 21601005.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 25296 + ... + 26135.

It is an arithmetic number, because the mean of its divisors is an integer number (1440096).

Almost surely, 2^21601020 is an apocalyptic number.

21601020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21601020 is an abundant number, since it is smaller than the sum of its proper divisors (47523588).

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

21601020 is a wasteful number, since it uses less digits than its factorization.

21601020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51450 (or 51448 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 12.

The square root of 21601020 is about 4647.6897486816. The cubic root of 21601020 is about 278.4997136706.

Adding to 21601020 its reverse (2010612), we get a palindrome (23611632).

The spelling of 21601020 in words is "twenty-one million, six hundred one thousand, twenty".