61691638 has 8 divisors (see below), whose sum is σ = 92668320. Its totient is φ = 30802200.

The previous prime is 61691621. The next prime is 61691701. The reversal of 61691638 is 83619616.

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

It is a cake number, because a cake can be divided into 61691638 parts by 718 planar cuts.

It is a self number, because there is not a number n which added to its sum of digits gives 61691638.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20013 + ... + 22888.

It is an arithmetic number, because the mean of its divisors is an integer number (11583540).

Almost surely, 2^61691638 is an apocalyptic number.

61691638 is a deficient number, since it is larger than the sum of its proper divisors (30976682).

61691638 is a wasteful number, since it uses less digits than its factorization.

61691638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43622.

The product of its digits is 46656, while the sum is 40.

The square root of 61691638 is about 7854.4024597674. The cubic root of 61691638 is about 395.1319070220.

The spelling of 61691638 in words is "sixty-one million, six hundred ninety-one thousand, six hundred thirty-eight".