61978666 has 4 divisors (see below), whose sum is σ = 92968002. Its totient is φ = 30989332.

The previous prime is 61978649. The next prime is 61978687. The reversal of 61978666 is 66687916.

61978666 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It can be written as a sum of positive squares in only one way, i.e., 34468641 + 27510025 = 5871^2 + 5245^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15494665 + ... + 15494668.

Almost surely, 2^61978666 is an apocalyptic number.

61978666 is a deficient number, since it is larger than the sum of its proper divisors (30989336).

61978666 is a wasteful number, since it uses less digits than its factorization.

61978666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30989335.

The product of its digits is 653184, while the sum is 49.

The square root of 61978666 is about 7872.6530470992. The cubic root of 61978666 is about 395.7437591689.

The spelling of 61978666 in words is "sixty-one million, nine hundred seventy-eight thousand, six hundred sixty-six".