61551512021 has 2 divisors, whose sum is σ = 61551512022. Its totient is φ = 61551512020.

The previous prime is 61551511993. The next prime is 61551512069. The reversal of 61551512021 is 12021515516.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 31272031921 + 30279480100 = 176839^2 + 174010^2 .

It is a cyclic number.

It is not a de Polignac number, because 61551512021 - 2²² = 61547317717 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61551517021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30775756010 + 30775756011.

It is an arithmetic number, because the mean of its divisors is an integer number (30775756011).

Almost surely, 2^61551512021 is an apocalyptic number.

It is an amenable number.

61551512021 is a deficient number, since it is larger than the sum of its proper divisors (1).

61551512021 is an equidigital number, since it uses as much as digits as its factorization.

61551512021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3000, while the sum is 29.

The spelling of 61551512021 in words is "sixty-one billion, five hundred fifty-one million, five hundred twelve thousand, twenty-one".