21520422 has 48 divisors (see below), whose sum is σ = 58136832. Its totient is φ = 5589360.

The previous prime is 21520399. The next prime is 21520423. The reversal of 21520422 is 22402512.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21520395 and 21520404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21520423) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6378 + ... + 9149.

It is an arithmetic number, because the mean of its divisors is an integer number (1211184).

Almost surely, 2^21520422 is an apocalyptic number.

21520422 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21520422 is an abundant number, since it is smaller than the sum of its proper divisors (36616410).

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

21520422 is a wasteful number, since it uses less digits than its factorization.

21520422 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15553 (or 15550 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 18.

The square root of 21520422 is about 4639.0108859540. The cubic root of 21520422 is about 278.1529014133.

Adding to 21520422 its reverse (22402512), we get a palindrome (43922934).

The spelling of 21520422 in words is "twenty-one million, five hundred twenty thousand, four hundred twenty-two".