61649921 has 2 divisors, whose sum is σ = 61649922. Its totient is φ = 61649920.

The previous prime is 61649909. The next prime is 61649923. The reversal of 61649921 is 12994616.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 59459521 + 2190400 = 7711^2 + 1480^2 .

It is a cyclic number.

It is not a de Polignac number, because 61649921 - 2⁶ = 61649857 is a prime.

It is a Sophie Germain prime.

Together with 61649923, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (61649923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30824960 + 30824961.

It is an arithmetic number, because the mean of its divisors is an integer number (30824961).

Almost surely, 2^61649921 is an apocalyptic number.

It is an amenable number.

61649921 is a deficient number, since it is larger than the sum of its proper divisors (1).

61649921 is an equidigital number, since it uses as much as digits as its factorization.

61649921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 23328, while the sum is 38.

The square root of 61649921 is about 7851.7463662551. The cubic root of 61649921 is about 395.0428218276.

The spelling of 61649921 in words is "sixty-one million, six hundred forty-nine thousand, nine hundred twenty-one".