25691621 has 4 divisors (see below), whose sum is σ = 26808672. Its totient is φ = 24574572.

The previous prime is 25691587. The next prime is 25691639. The reversal of 25691621 is 12619652.

It is a happy number.

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 a cyclic number.

It is not a de Polignac number, because 25691621 - 2⁶ = 25691557 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25691221) 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, 558491 + ... + 558536.

It is an arithmetic number, because the mean of its divisors is an integer number (6702168).

Almost surely, 2^25691621 is an apocalyptic number.

It is an amenable number.

25691621 is a deficient number, since it is larger than the sum of its proper divisors (1117051).

25691621 is a wasteful number, since it uses less digits than its factorization.

25691621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1117050.

The product of its digits is 6480, while the sum is 32.

The square root of 25691621 is about 5068.6902647528. The cubic root of 25691621 is about 295.0736998662.

The spelling of 25691621 in words is "twenty-five million, six hundred ninety-one thousand, six hundred twenty-one".