61778440 has 32 divisors (see below), whose sum is σ = 140912280. Its totient is φ = 24371712.

The previous prime is 61778417. The next prime is 61778471. The reversal of 61778440 is 4487716.

It can be written as a sum of positive squares in 4 ways, for example, as 33709636 + 28068804 = 5806^2 + 5298^2 .

It is a Smith number, since the sum of its digits (37) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 61778440.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7659 + ... + 13498.

Almost surely, 2^61778440 is an apocalyptic number.

It is an amenable number.

61778440 is an abundant number, since it is smaller than the sum of its proper divisors (79133840).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

61778440 is a wasteful number, since it uses less digits than its factorization.

61778440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21241 (or 21237 counting only the distinct ones).

The product of its (nonzero) digits is 37632, while the sum is 37.

The square root of 61778440 is about 7859.9262083050. The cubic root of 61778440 is about 395.3171410194.

The spelling of 61778440 in words is "sixty-one million, seven hundred seventy-eight thousand, four hundred forty".