61866437583391 has 16 divisors (see below), whose sum is σ = 70715687777280. Its totient is φ = 53019985112640.

The previous prime is 61866437583389. The next prime is 61866437583403. The reversal of 61866437583391 is 19338573466816.

It is not a de Polignac number, because 61866437583391 - 2¹ = 61866437583389 is a prime.

It is a super-2 number, since 2×61866437583391² (a number of 28 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 61866437583391.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61866537583391) 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 in 15 ways as a sum of consecutive naturals, for example, 2008048395 + ... + 2008079203.

It is an arithmetic number, because the mean of its divisors is an integer number (4419730486080).

Almost surely, 2^{61866437583391} is an apocalyptic number.

61866437583391 is a deficient number, since it is larger than the sum of its proper divisors (8849250193889).

61866437583391 is a wasteful number, since it uses less digits than its factorization.

61866437583391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66894.

The product of its digits is 470292480, while the sum is 70.

The spelling of 61866437583391 in words is "sixty-one trillion, eight hundred sixty-six billion, four hundred thirty-seven million, five hundred eighty-three thousand, three hundred ninety-one".