61651338821 has 2 divisors, whose sum is σ = 61651338822. Its totient is φ = 61651338820.

The previous prime is 61651338809. The next prime is 61651338857. The reversal of 61651338821 is 12883315616.

61651338821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 50135688100 + 11515650721 = 223910^2 + 107311^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61651338821 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61651334821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30825669410 + 30825669411.

It is an arithmetic number, because the mean of its divisors is an integer number (30825669411).

Almost surely, 2^61651338821 is an apocalyptic number.

It is an amenable number.

61651338821 is a deficient number, since it is larger than the sum of its proper divisors (1).

61651338821 is an equidigital number, since it uses as much as digits as its factorization.

61651338821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 207360, while the sum is 44.

The spelling of 61651338821 in words is "sixty-one billion, six hundred fifty-one million, three hundred thirty-eight thousand, eight hundred twenty-one".