61987729 has 4 divisors (see below), whose sum is σ = 65634084. Its totient is φ = 58341376.

The previous prime is 61987721. The next prime is 61987789. The reversal of 61987729 is 92778916.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 48650625 + 13337104 = 6975^2 + 3652^2 .

It is a cyclic number.

It is not a de Polignac number, because 61987729 - 2³ = 61987721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (61987721) 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, 1823152 + ... + 1823185.

It is an arithmetic number, because the mean of its divisors is an integer number (16408521).

Almost surely, 2^61987729 is an apocalyptic number.

It is an amenable number.

61987729 is a deficient number, since it is larger than the sum of its proper divisors (3646355).

61987729 is a wasteful number, since it uses less digits than its factorization.

61987729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3646354.

The product of its digits is 381024, while the sum is 49.

The square root of 61987729 is about 7873.2286261736. The cubic root of 61987729 is about 395.7630478001.

The spelling of 61987729 in words is "sixty-one million, nine hundred eighty-seven thousand, seven hundred twenty-nine".