21522020 has 96 divisors (see below), whose sum is σ = 52496640. Its totient is φ = 7349760.

The previous prime is 21522001. The next prime is 21522037. The reversal of 21522020 is 2022512.

It is a junction number, because it is equal to n+sod(n) for n = 21521986 and 21522004.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 352790 + ... + 352850.

It is an arithmetic number, because the mean of its divisors is an integer number (546840).

Almost surely, 2^21522020 is an apocalyptic number.

21522020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21522020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26248320).

21522020 is an abundant number, since it is smaller than the sum of its proper divisors (30974620).

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

21522020 is a wasteful number, since it uses less digits than its factorization.

21522020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165 (or 163 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 14.

The square root of 21522020 is about 4639.1831177482. The cubic root of 21522020 is about 278.1597859954.

Adding to 21522020 its reverse (2022512), we get a palindrome (23544532).

The spelling of 21522020 in words is "twenty-one million, five hundred twenty-two thousand, twenty".