61154121661 has 2 divisors, whose sum is σ = 61154121662. Its totient is φ = 61154121660.

The previous prime is 61154121599. The next prime is 61154121667. The reversal of 61154121661 is 16612145116.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 57871519225 + 3282602436 = 240565^2 + 57294^2 .

It is a cyclic number.

It is not a de Polignac number, because 61154121661 - 2²³ = 61145733053 is a prime.

It is a super-2 number, since 2×61154121661² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61154121667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30577060830 + 30577060831.

It is an arithmetic number, because the mean of its divisors is an integer number (30577060831).

Almost surely, 2^61154121661 is an apocalyptic number.

It is an amenable number.

61154121661 is a deficient number, since it is larger than the sum of its proper divisors (1).

61154121661 is an equidigital number, since it uses as much as digits as its factorization.

61154121661 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.

Adding to 61154121661 its reverse (16612145116), we get a palindrome (77766266777).

The spelling of 61154121661 in words is "sixty-one billion, one hundred fifty-four million, one hundred twenty-one thousand, six hundred sixty-one".