20696581 has 2 divisors, whose sum is σ = 20696582. Its totient is φ = 20696580.

The previous prime is 20696549. The next prime is 20696587. The reversal of 20696581 is 18569602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15249025 + 5447556 = 3905^2 + 2334^2 .

It is a cyclic number.

It is not a de Polignac number, because 20696581 - 2⁵ = 20696549 is a prime.

It is a super-2 number, since 2×20696581² = 856696930179122, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20696581.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20696587) 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 as a sum of consecutive naturals, namely, 10348290 + 10348291.

It is an arithmetic number, because the mean of its divisors is an integer number (10348291).

Almost surely, 2^20696581 is an apocalyptic number.

It is an amenable number.

20696581 is a deficient number, since it is larger than the sum of its proper divisors (1).

20696581 is an equidigital number, since it uses as much as digits as its factorization.

20696581 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 25920, while the sum is 37.

The square root of 20696581 is about 4549.3495139415. The cubic root of 20696581 is about 274.5572202417.

It can be divided in two parts, 206965 and 81, that added together give a triangular number (207046 = T₆₄₃).

The spelling of 20696581 in words is "twenty million, six hundred ninety-six thousand, five hundred eighty-one".