61728391 has 2 divisors, whose sum is σ = 61728392. Its totient is φ = 61728390.

The previous prime is 61728367. The next prime is 61728413. The reversal of 61728391 is 19382716.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 61728391 - 2⁹ = 61727879 is a prime.

It is a Chen prime.

It is equal to p_3658447 and since 61728391 and 3658447 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 61728391.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61722391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30864195 + 30864196.

It is an arithmetic number, because the mean of its divisors is an integer number (30864196).

Almost surely, 2^61728391 is an apocalyptic number.

61728391 is a deficient number, since it is larger than the sum of its proper divisors (1).

61728391 is an equidigital number, since it uses as much as digits as its factorization.

61728391 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18144, while the sum is 37.

The square root of 61728391 is about 7856.7417546970. The cubic root of 61728391 is about 395.2103584973.

The spelling of 61728391 in words is "sixty-one million, seven hundred twenty-eight thousand, three hundred ninety-one".