40643749 has 2 divisors, whose sum is σ = 40643750. Its totient is φ = 40643748.

The previous prime is 40643747. The next prime is 40643777. The reversal of 40643749 is 94734604.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 23213124 + 17430625 = 4818^2 + 4175^2 .

It is a cyclic number.

It is not a de Polignac number, because 40643749 - 2¹ = 40643747 is a prime.

Together with 40643747, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (40643747) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20321874 + 20321875.

It is an arithmetic number, because the mean of its divisors is an integer number (20321875).

Almost surely, 2^40643749 is an apocalyptic number.

It is an amenable number.

40643749 is a deficient number, since it is larger than the sum of its proper divisors (1).

40643749 is an equidigital number, since it uses as much as digits as its factorization.

40643749 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72576, while the sum is 37.

The square root of 40643749 is about 6375.2450148994. The cubic root of 40643749 is about 343.8200930785.

The spelling of 40643749 in words is "forty million, six hundred forty-three thousand, seven hundred forty-nine".