61809281 has 2 divisors, whose sum is σ = 61809282. Its totient is φ = 61809280.

The previous prime is 61809247. The next prime is 61809301. The reversal of 61809281 is 18290816.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 54626881 + 7182400 = 7391^2 + 2680^2 .

It is a cyclic number.

It is not a de Polignac number, because 61809281 - 2⁶ = 61809217 is a prime.

It is a super-2 number, since 2×61809281² = 7640774435473922, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is equal to p_3662945 and since 61809281 and 3662945 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (61809581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30904640 + 30904641.

It is an arithmetic number, because the mean of its divisors is an integer number (30904641).

Almost surely, 2^61809281 is an apocalyptic number.

It is an amenable number.

61809281 is a deficient number, since it is larger than the sum of its proper divisors (1).

61809281 is an equidigital number, since it uses as much as digits as its factorization.

61809281 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6912, while the sum is 35.

The square root of 61809281 is about 7861.8878776029. The cubic root of 61809281 is about 395.3829134134.

The spelling of 61809281 in words is "sixty-one million, eight hundred nine thousand, two hundred eighty-one".