61638281 has 2 divisors, whose sum is σ = 61638282. Its totient is φ = 61638280.

The previous prime is 61638259. The next prime is 61638289. The reversal of 61638281 is 18283616.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 47045881 + 14592400 = 6859^2 + 3820^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61638281 is a prime.

It is a super-2 number, since 2×61638281² = 7598555369269922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (61638289) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30819140 + 30819141.

It is an arithmetic number, because the mean of its divisors is an integer number (30819141).

Almost surely, 2^61638281 is an apocalyptic number.

It is an amenable number.

61638281 is a deficient number, since it is larger than the sum of its proper divisors (1).

61638281 is an equidigital number, since it uses as much as digits as its factorization.

61638281 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13824, while the sum is 35.

The square root of 61638281 is about 7851.0050948907. The cubic root of 61638281 is about 395.0179578440.

The spelling of 61638281 in words is "sixty-one million, six hundred thirty-eight thousand, two hundred eighty-one".