25215551 has 4 divisors (see below), whose sum is σ = 25356600. Its totient is φ = 25074504.

The previous prime is 25215503. The next prime is 25215557. The reversal of 25215551 is 15551252.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-25215551 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 25215551.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25215557) 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 3 ways as a sum of consecutive naturals, for example, 70256 + ... + 70613.

It is an arithmetic number, because the mean of its divisors is an integer number (6339150).

Almost surely, 2^25215551 is an apocalyptic number.

25215551 is a deficient number, since it is larger than the sum of its proper divisors (141049).

25215551 is a wasteful number, since it uses less digits than its factorization.

25215551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 141048.

The product of its digits is 2500, while the sum is 26.

The square root of 25215551 is about 5021.5088369931. The cubic root of 25215551 is about 293.2397366960.

The spelling of 25215551 in words is "twenty-five million, two hundred fifteen thousand, five hundred fifty-one".