61516661 has 4 divisors (see below), whose sum is σ = 64754400. Its totient is φ = 58278924.

The previous prime is 61516649. The next prime is 61516667. The reversal of 61516661 is 16661516.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61516661 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61516667) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1618841 + ... + 1618878.

It is an arithmetic number, because the mean of its divisors is an integer number (16188600).

Almost surely, 2^61516661 is an apocalyptic number.

It is an amenable number.

61516661 is a deficient number, since it is larger than the sum of its proper divisors (3237739).

61516661 is a wasteful number, since it uses less digits than its factorization.

61516661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3237738.

The product of its digits is 6480, while the sum is 32.

The square root of 61516661 is about 7843.2557653056. The cubic root of 61516661 is about 394.7579802478.

The spelling of 61516661 in words is "sixty-one million, five hundred sixteen thousand, six hundred sixty-one".