61687993 has 4 divisors (see below), whose sum is σ = 62533108. Its totient is φ = 60842880.

The previous prime is 61687987. The next prime is 61687999. The reversal of 61687993 is 39978616.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (61687987) and next prime (61687999).

It can be written as a sum of positive squares in 2 ways, for example, as 17239104 + 44448889 = 4152^2 + 6667^2 .

It is a cyclic number.

It is not a de Polignac number, because 61687993 - 2²⁵ = 28133561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (61687999) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 422448 + ... + 422593.

It is an arithmetic number, because the mean of its divisors is an integer number (15633277).

Almost surely, 2^61687993 is an apocalyptic number.

It is an amenable number.

61687993 is a deficient number, since it is larger than the sum of its proper divisors (845115).

61687993 is an equidigital number, since it uses as much as digits as its factorization.

61687993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 845114.

The product of its digits is 489888, while the sum is 49.

The square root of 61687993 is about 7854.1704208656. The cubic root of 61687993 is about 395.1241248535.

It can be divided in two parts, 6168 and 7993, that added together give a square (14161 = 119²).

The spelling of 61687993 in words is "sixty-one million, six hundred eighty-seven thousand, nine hundred ninety-three".