61616161 has 16 divisors (see below), whose sum is σ = 64580688. Its totient is φ = 58752000.

The previous prime is 61616141. The next prime is 61616167. The reversal of 61616161 is 16161616.

It can be written as a sum of positive squares in 8 ways, for example, as 291600 + 61324561 = 540^2 + 7831^2 .

It is a 3-Lehmer number, since φ(61616161) divides (61616161-1)³.

It is a cyclic number.

It is not a de Polignac number, because 61616161 - 2²⁵ = 28061729 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a deceptive number, since it divides R_61616160.

It is a Duffinian number.

61616161 is an undulating number in base 10.

61616161 is a modest number, since divided by 616161 gives 61 as remainder.

It is not an unprimeable number, because it can be changed into a prime (61616167) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 449685 + ... + 449821.

It is an arithmetic number, because the mean of its divisors is an integer number (4036293).

Almost surely, 2^61616161 is an apocalyptic number.

61616161 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

61616161 is a deficient number, since it is larger than the sum of its proper divisors (2964527).

61616161 is a wasteful number, since it uses less digits than its factorization.

61616161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 372.

The product of its digits is 1296, while the sum is 28.

The square root of 61616161 is about 7849.5962316542. The cubic root of 61616161 is about 394.9706991030.

Adding to 61616161 its reverse (16161616), we get a palindrome (77777777).

The spelling of 61616161 in words is "sixty-one million, six hundred sixteen thousand, one hundred sixty-one".