20279681 has 2 divisors, whose sum is σ = 20279682. Its totient is φ = 20279680.

The previous prime is 20279653. The next prime is 20279687. The reversal of 20279681 is 18697202.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19360000 + 919681 = 4400^2 + 959^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20279681 is a prime.

It is a super-2 number, since 2×20279681² = 822530922923522, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20279687) 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 as a sum of consecutive naturals, namely, 10139840 + 10139841.

It is an arithmetic number, because the mean of its divisors is an integer number (10139841).

Almost surely, 2^20279681 is an apocalyptic number.

It is an amenable number.

20279681 is a deficient number, since it is larger than the sum of its proper divisors (1).

20279681 is an equidigital number, since it uses as much as digits as its factorization.

20279681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12096, while the sum is 35.

The square root of 20279681 is about 4503.2966813214. The cubic root of 20279681 is about 272.7011941764.

The spelling of 20279681 in words is "twenty million, two hundred seventy-nine thousand, six hundred eighty-one".