61638145 has 4 divisors (see below), whose sum is σ = 73965780. Its totient is φ = 49310512.

The previous prime is 61638139. The next prime is 61638149. The reversal of 61638145 is 54183616.

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 41576704 + 20061441 = 6448^2 + 4479^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61638145 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a self number, because there is not a number n which added to its sum of digits gives 61638145.

It is not an unprimeable number, because it can be changed into a prime (61638149) 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, 6163810 + ... + 6163819.

It is an arithmetic number, because the mean of its divisors is an integer number (18491445).

Almost surely, 2^61638145 is an apocalyptic number.

It is an amenable number.

61638145 is a deficient number, since it is larger than the sum of its proper divisors (12327635).

61638145 is a wasteful number, since it uses less digits than its factorization.

61638145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12327634.

The product of its digits is 17280, while the sum is 34.

The square root of 61638145 is about 7850.9964335745. The cubic root of 61638145 is about 395.0176673185.

The spelling of 61638145 in words is "sixty-one million, six hundred thirty-eight thousand, one hundred forty-five".