61111661 has 8 divisors (see below), whose sum is σ = 65908920. Its totient is φ = 56328192.

The previous prime is 61111637. The next prime is 61111681. The reversal of 61111661 is 16611116.

It can be written as a sum of positive squares in 4 ways, for example, as 1729225 + 59382436 = 1315^2 + 7706^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 61111661 - 2¹⁴ = 61095277 is a prime.

It is a super-2 number, since 2×61111661² = 7469270220357842, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61111601) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6941 + ... + 13053.

It is an arithmetic number, because the mean of its divisors is an integer number (8238615).

Almost surely, 2^61111661 is an apocalyptic number.

It is an amenable number.

61111661 is a deficient number, since it is larger than the sum of its proper divisors (4797259).

61111661 is a wasteful number, since it uses less digits than its factorization.

61111661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6895.

The product of its digits is 216, while the sum is 23.

The square root of 61111661 is about 7817.3947706381. The cubic root of 61111661 is about 393.8897649127.

Adding to 61111661 its reverse (16611116), we get a palindrome (77722777).

The spelling of 61111661 in words is "sixty-one million, one hundred eleven thousand, six hundred sixty-one".