61781807 has 4 divisors (see below), whose sum is σ = 62196600. Its totient is φ = 61367016.

The previous prime is 61781789. The next prime is 61781813. The reversal of 61781807 is 70818716.

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

It is a cyclic number.

It is not a de Polignac number, because 61781807 - 2¹⁶ = 61716271 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61781207) 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, 207173 + ... + 207470.

It is an arithmetic number, because the mean of its divisors is an integer number (15549150).

Almost surely, 2^61781807 is an apocalyptic number.

61781807 is a deficient number, since it is larger than the sum of its proper divisors (414793).

61781807 is a wasteful number, since it uses less digits than its factorization.

61781807 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 414792.

The product of its (nonzero) digits is 18816, while the sum is 38.

The square root of 61781807 is about 7860.1403931482. The cubic root of 61781807 is about 395.3243226437.

The spelling of 61781807 in words is "sixty-one million, seven hundred eighty-one thousand, eight hundred seven".