21220040 has 16 divisors (see below), whose sum is σ = 47745180. Its totient is φ = 8488000.

The previous prime is 21220019. The next prime is 21220103. The reversal of 21220040 is 4002212.

It can be written as a sum of positive squares in 2 ways, for example, as 20232004 + 988036 = 4498^2 + 994^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 265211 + ... + 265290.

Almost surely, 2^21220040 is an apocalyptic number.

21220040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21220040 is an abundant number, since it is smaller than the sum of its proper divisors (26525140).

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

21220040 is a wasteful number, since it uses less digits than its factorization.

21220040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 530512 (or 530508 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 11.

The square root of 21220040 is about 4606.5214641853. The cubic root of 21220040 is about 276.8526805075.

Adding to 21220040 its reverse (4002212), we get a palindrome (25222252).

The spelling of 21220040 in words is "twenty-one million, two hundred twenty thousand, forty".