25520815 has 4 divisors (see below), whose sum is σ = 30624984. Its totient is φ = 20416648.

The previous prime is 25520779. The next prime is 25520827. The reversal of 25520815 is 51802552.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 25520815 - 2¹⁷ = 25389743 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2552077 + ... + 2552086.

It is an arithmetic number, because the mean of its divisors is an integer number (7656246).

Almost surely, 2^25520815 is an apocalyptic number.

25520815 is a deficient number, since it is larger than the sum of its proper divisors (5104169).

25520815 is an equidigital number, since it uses as much as digits as its factorization.

25520815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5104168.

The product of its (nonzero) digits is 4000, while the sum is 28.

The square root of 25520815 is about 5051.8130408795. The cubic root of 25520815 is about 294.4183310043.

It can be divided in two parts, 25520 and 815, that added together give a triangular number (26335 = T₂₂₉).

The spelling of 25520815 in words is "twenty-five million, five hundred twenty thousand, eight hundred fifteen".