25781990 has 16 divisors (see below), whose sum is σ = 49977648. Its totient is φ = 9519456.

The previous prime is 25781963. The next prime is 25781999. The reversal of 25781990 is 9918752.

It is a super-2 number, since 2×25781990² = 1329422016720200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25781999) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 99032 + ... + 99291.

It is an arithmetic number, because the mean of its divisors is an integer number (3123603).

Almost surely, 2^25781990 is an apocalyptic number.

25781990 is a deficient number, since it is larger than the sum of its proper divisors (24195658).

25781990 is a wasteful number, since it uses less digits than its factorization.

25781990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 198343.

The product of its (nonzero) digits is 45360, while the sum is 41.

The square root of 25781990 is about 5077.5968725372. The cubic root of 25781990 is about 295.4192640388.

The spelling of 25781990 in words is "twenty-five million, seven hundred eighty-one thousand, nine hundred ninety".