61615681 has 2 divisors, whose sum is σ = 61615682. Its totient is φ = 61615680.

The previous prime is 61615669. The next prime is 61615699. The reversal of 61615681 is 18651616.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 48720400 + 12895281 = 6980^2 + 3591^2 .

It is a cyclic number.

It is not a de Polignac number, because 61615681 - 2⁷ = 61615553 is a prime.

It is a super-2 number, since 2×61615681² = 7592984290187522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (61615381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30807840 + 30807841.

It is an arithmetic number, because the mean of its divisors is an integer number (30807841).

Almost surely, 2^61615681 is an apocalyptic number.

It is an amenable number.

61615681 is a deficient number, since it is larger than the sum of its proper divisors (1).

61615681 is an equidigital number, since it uses as much as digits as its factorization.

61615681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8640, while the sum is 34.

The square root of 61615681 is about 7849.5656567736. The cubic root of 61615681 is about 394.9696734715.

The spelling of 61615681 in words is "sixty-one million, six hundred fifteen thousand, six hundred eighty-one".