21559425 has 24 divisors (see below), whose sum is σ = 35813184. Its totient is φ = 11444160.

The previous prime is 21559423. The next prime is 21559427. The reversal of 21559425 is 52495512.

It is an interprime number because it is at equal distance from previous prime (21559423) and next prime (21559427).

It is not a de Polignac number, because 21559425 - 2¹ = 21559423 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21559423) 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, 19179 + ... + 20271.

It is an arithmetic number, because the mean of its divisors is an integer number (1492216).

Almost surely, 2^21559425 is an apocalyptic number.

21559425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21559425 is a deficient number, since it is larger than the sum of its proper divisors (14253759).

21559425 is a wasteful number, since it uses less digits than its factorization.

21559425 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1369 (or 1364 counting only the distinct ones).

The product of its digits is 18000, while the sum is 33.

The square root of 21559425 is about 4643.2127885765. The cubic root of 21559425 is about 278.3208387983.

The spelling of 21559425 in words is "twenty-one million, five hundred fifty-nine thousand, four hundred twenty-five".