25718421 has 4 divisors (see below), whose sum is σ = 34291232. Its totient is φ = 17145612.

The previous prime is 25718417. The next prime is 25718423. The reversal of 25718421 is 12481752.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 25718421 - 2² = 25718417 is a prime.

It is a super-3 number, since 3×25718421³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25718423) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4286401 + ... + 4286406.

It is an arithmetic number, because the mean of its divisors is an integer number (8572808).

Almost surely, 2^25718421 is an apocalyptic number.

It is an amenable number.

25718421 is a deficient number, since it is larger than the sum of its proper divisors (8572811).

25718421 is an equidigital number, since it uses as much as digits as its factorization.

25718421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8572810.

The product of its digits is 4480, while the sum is 30.

The square root of 25718421 is about 5071.3332566496. Note that the first 3 decimals coincide. The cubic root of 25718421 is about 295.1762654334.

The spelling of 25718421 in words is "twenty-five million, seven hundred eighteen thousand, four hundred twenty-one".