21445425 has 24 divisors (see below), whose sum is σ = 39397280. Its totient is φ = 11437200.

The previous prime is 21445409. The next prime is 21445441. The reversal of 21445425 is 52454412.

It is an interprime number because it is at equal distance from previous prime (21445409) and next prime (21445441).

It is not a de Polignac number, because 21445425 - 2⁴ = 21445409 is a prime.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 15211 + ... + 16560.

Almost surely, 2^21445425 is an apocalyptic number.

21445425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21445425 is a deficient number, since it is larger than the sum of its proper divisors (17951855).

21445425 is a wasteful number, since it uses less digits than its factorization.

21445425 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31790 (or 31779 counting only the distinct ones).

The product of its digits is 6400, while the sum is 27.

The square root of 21445425 is about 4630.9205348397. The cubic root of 21445425 is about 277.8294115868.

Adding to 21445425 its reverse (52454412), we get a palindrome (73899837).

It can be divided in two parts, 2144 and 5425, that added together give a square (7569 = 87²).

The spelling of 21445425 in words is "twenty-one million, four hundred forty-five thousand, four hundred twenty-five".