21526420 has 24 divisors (see below), whose sum is σ = 47865384. Its totient is φ = 8103936.

The previous prime is 21526397. The next prime is 21526429. The reversal of 21526420 is 2462512.

It can be written as a sum of positive squares in 4 ways, for example, as 8305924 + 13220496 = 2882^2 + 3636^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21526391 and 21526400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21526429) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31317 + ... + 31996.

It is an arithmetic number, because the mean of its divisors is an integer number (1994391).

Almost surely, 2^21526420 is an apocalyptic number.

21526420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21526420 is an abundant number, since it is smaller than the sum of its proper divisors (26338964).

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

21526420 is a wasteful number, since it uses less digits than its factorization.

21526420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63339 (or 63337 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 22.

The square root of 21526420 is about 4639.6573149318. The cubic root of 21526420 is about 278.1787405306.

Adding to 21526420 its reverse (2462512), we get a palindrome (23988932).

The spelling of 21526420 in words is "twenty-one million, five hundred twenty-six thousand, four hundred twenty".