61507891 has 2 divisors, whose sum is σ = 61507892. Its totient is φ = 61507890.

The previous prime is 61507879. The next prime is 61507903. The reversal of 61507891 is 19870516.

61507891 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a balanced prime because it is at equal distance from previous prime (61507879) and next prime (61507903).

It is a cyclic number.

It is not a de Polignac number, because 61507891 - 2¹³ = 61499699 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 61507891.

It is not a weakly prime, because it can be changed into another prime (61507841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30753945 + 30753946.

It is an arithmetic number, because the mean of its divisors is an integer number (30753946).

Almost surely, 2^61507891 is an apocalyptic number.

61507891 is a deficient number, since it is larger than the sum of its proper divisors (1).

61507891 is an equidigital number, since it uses as much as digits as its factorization.

61507891 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15120, while the sum is 37.

The square root of 61507891 is about 7842.6966663259. The cubic root of 61507891 is about 394.7392200618.

Subtracting from 61507891 its reverse (19870516), we obtain a triangular number (41637375 = T₉₁₂₅).

It can be divided in two parts, 6150 and 7891, that added together give a palindrome (14041).

The spelling of 61507891 in words is "sixty-one million, five hundred seven thousand, eight hundred ninety-one".