25721839 has 16 divisors (see below), whose sum is σ = 31812480. Its totient is φ = 20446560.

The previous prime is 25721827. The next prime is 25721849. The reversal of 25721839 is 93812752.

25721839 = 2068² + 2069² + ... + 2073².

It is a cyclic number.

It is not a de Polignac number, because 25721839 - 2⁵ = 25721807 is a prime.

It is a super-2 number, since 2×25721839² = 1323226003083842, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 25721798 and 25721807.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25721849) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2017 + ... + 7450.

It is an arithmetic number, because the mean of its divisors is an integer number (1988280).

Almost surely, 2^25721839 is an apocalyptic number.

25721839 is a deficient number, since it is larger than the sum of its proper divisors (6090641).

25721839 is a wasteful number, since it uses less digits than its factorization.

25721839 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9510.

The product of its digits is 30240, while the sum is 37.

The square root of 25721839 is about 5071.6702377028. The cubic root of 25721839 is about 295.1893412463.

The spelling of 25721839 in words is "twenty-five million, seven hundred twenty-one thousand, eight hundred thirty-nine".