20499749 has 2 divisors, whose sum is σ = 20499750. Its totient is φ = 20499748.

The previous prime is 20499697. The next prime is 20499757. The reversal of 20499749 is 94799402.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10355524 + 10144225 = 3218^2 + 3185^2 .

It is a cyclic number.

It is not a de Polignac number, because 20499749 - 2¹² = 20495653 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20499779) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10249874 + 10249875.

It is an arithmetic number, because the mean of its divisors is an integer number (10249875).

Almost surely, 2^20499749 is an apocalyptic number.

It is an amenable number.

20499749 is a deficient number, since it is larger than the sum of its proper divisors (1).

20499749 is an equidigital number, since it uses as much as digits as its factorization.

20499749 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 163296, while the sum is 44.

The square root of 20499749 is about 4527.6648506708. The cubic root of 20499749 is about 273.6840667438.

The spelling of 20499749 in words is "twenty million, four hundred ninety-nine thousand, seven hundred forty-nine".