61638891 has 8 divisors (see below), whose sum is σ = 85019280. Its totient is φ = 39675552.

The previous prime is 61638877. The next prime is 61638931. The reversal of 61638891 is 19883616.

61638891 is nontrivially palindromic in base 4.

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

It is not a de Polignac number, because 61638891 - 2⁵ = 61638859 is a prime.

It is not an unprimeable number, because it can be changed into a prime (61638851) 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, 354160 + ... + 354333.

It is an arithmetic number, because the mean of its divisors is an integer number (10627410).

Almost surely, 2^61638891 is an apocalyptic number.

61638891 is a deficient number, since it is larger than the sum of its proper divisors (23380389).

61638891 is a wasteful number, since it uses less digits than its factorization.

61638891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 708525.

The product of its digits is 62208, while the sum is 42.

The square root of 61638891 is about 7851.0439433237. The cubic root of 61638891 is about 395.0192609312.

The spelling of 61638891 in words is "sixty-one million, six hundred thirty-eight thousand, eight hundred ninety-one".