61394432821 has 2 divisors, whose sum is σ = 61394432822. Its totient is φ = 61394432820.

The previous prime is 61394432807. The next prime is 61394432833. The reversal of 61394432821 is 12823449316.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 39398280100 + 21996152721 = 198490^2 + 148311^2 .

It is a cyclic number.

It is not a de Polignac number, because 61394432821 - 2²⁵ = 61360878389 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61394432881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30697216410 + 30697216411.

It is an arithmetic number, because the mean of its divisors is an integer number (30697216411).

Almost surely, 2^61394432821 is an apocalyptic number.

It is an amenable number.

61394432821 is a deficient number, since it is larger than the sum of its proper divisors (1).

61394432821 is an equidigital number, since it uses as much as digits as its factorization.

61394432821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 248832, while the sum is 43.

The spelling of 61394432821 in words is "sixty-one billion, three hundred ninety-four million, four hundred thirty-two thousand, eight hundred twenty-one".