61638809 has 2 divisors, whose sum is σ = 61638810. Its totient is φ = 61638808.

The previous prime is 61638779. The next prime is 61638839. The reversal of 61638809 is 90883616.

It is a happy number.

It is a balanced prime because it is at equal distance from previous prime (61638779) and next prime (61638839).

It can be written as a sum of positive squares in only one way, i.e., 36638809 + 25000000 = 6053^2 + 5000^2 .

It is a cyclic number.

It is not a de Polignac number, because 61638809 - 2¹⁶ = 61573273 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (61638839) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30819404 + 30819405.

It is an arithmetic number, because the mean of its divisors is an integer number (30819405).

Almost surely, 2^61638809 is an apocalyptic number.

It is an amenable number.

61638809 is a deficient number, since it is larger than the sum of its proper divisors (1).

61638809 is an equidigital number, since it uses as much as digits as its factorization.

61638809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 62208, while the sum is 41.

The square root of 61638809 is about 7851.0387210865. The cubic root of 61638809 is about 395.0190857626.

The spelling of 61638809 in words is "sixty-one million, six hundred thirty-eight thousand, eight hundred nine".