61389991 has 8 divisors (see below), whose sum is σ = 66173184. Its totient is φ = 56615520.

The previous prime is 61389989. The next prime is 61390001. The reversal of 61389991 is 19998316.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 61389991 - 2¹ = 61389989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61389971) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26325 + ... + 28561.

It is an arithmetic number, because the mean of its divisors is an integer number (8271648).

Almost surely, 2^61389991 is an apocalyptic number.

61389991 is a deficient number, since it is larger than the sum of its proper divisors (4783193).

61389991 is a wasteful number, since it uses less digits than its factorization.

61389991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4361.

The product of its digits is 104976, while the sum is 46.

The square root of 61389991 is about 7835.1765136466. The cubic root of 61389991 is about 394.4868431108.

It can be divided in two parts, 6138 and 9991, that added together give a square (16129 = 127²).

The spelling of 61389991 in words is "sixty-one million, three hundred eighty-nine thousand, nine hundred ninety-one".