25172989921 has 4 divisors (see below), whose sum is σ = 26653754052. Its totient is φ = 23692225792.

The previous prime is 25172989903. The next prime is 25172989931. The reversal of 25172989921 is 12998927152.

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

It can be written as a sum of positive squares in 2 ways, for example, as 13928720400 + 11244269521 = 118020^2 + 106039^2 .

It is a cyclic number.

It is not a de Polignac number, because 25172989921 - 2¹⁵ = 25172957153 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (25172989931) 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, 740382040 + ... + 740382073.

It is an arithmetic number, because the mean of its divisors is an integer number (6663438513).

Almost surely, 2^25172989921 is an apocalyptic number.

It is an amenable number.

25172989921 is a deficient number, since it is larger than the sum of its proper divisors (1480764131).

25172989921 is a wasteful number, since it uses less digits than its factorization.

25172989921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1480764130.

The product of its digits is 1632960, while the sum is 55.

The spelling of 25172989921 in words is "twenty-five billion, one hundred seventy-two million, nine hundred eighty-nine thousand, nine hundred twenty-one".