20280749 has 2 divisors, whose sum is σ = 20280750. Its totient is φ = 20280748.

The previous prime is 20280737. The next prime is 20280751. The reversal of 20280749 is 94708202.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19669225 + 611524 = 4435^2 + 782^2 .

It is a cyclic number.

It is not a de Polignac number, because 20280749 - 2⁸ = 20280493 is a prime.

It is a super-2 number, since 2×20280749² = 822617560002002, which contains 22 as substring.

Together with 20280751, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20280149) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10140374 + 10140375.

It is an arithmetic number, because the mean of its divisors is an integer number (10140375).

Almost surely, 2^20280749 is an apocalyptic number.

It is an amenable number.

20280749 is a deficient number, since it is larger than the sum of its proper divisors (1).

20280749 is an equidigital number, since it uses as much as digits as its factorization.

20280749 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8064, while the sum is 32.

The square root of 20280749 is about 4503.4152595558. The cubic root of 20280749 is about 272.7059812301.

The spelling of 20280749 in words is "twenty million, two hundred eighty thousand, seven hundred forty-nine".