21573025 has 6 divisors (see below), whose sum is σ = 26750582. Its totient is φ = 17258400.

The previous prime is 21573023. The next prime is 21573029. The reversal of 21573025 is 52037512.

It can be written as a sum of positive squares in 3 ways, for example, as 788544 + 20784481 = 888^2 + 4559^2 .

It is not a de Polignac number, because 21573025 - 2¹ = 21573023 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (25), and also a Moran number because the ratio is a prime number: 862921 = 21573025 / (2 + 1 + 5 + 7 + 3 + 0 + 2 + 5).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21573023) by changing a digit.

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 5 ways as a sum of consecutive naturals, for example, 431436 + ... + 431485.

Almost surely, 2^21573025 is an apocalyptic number.

21573025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21573025 is a deficient number, since it is larger than the sum of its proper divisors (5177557).

21573025 is an equidigital number, since it uses as much as digits as its factorization.

21573025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 862931 (or 862926 counting only the distinct ones).

The product of its (nonzero) digits is 2100, while the sum is 25.

The square root of 21573025 is about 4644.6770608945. The cubic root of 21573025 is about 278.3793494462.

The spelling of 21573025 in words is "twenty-one million, five hundred seventy-three thousand, twenty-five".