61728357785 has 4 divisors (see below), whose sum is σ = 74074029348. Its totient is φ = 49382686224.

The previous prime is 61728357731. The next prime is 61728357793. The reversal of 61728357785 is 58775382716.

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 41285363344 + 20442994441 = 203188^2 + 142979^2 .

It is a cyclic number.

It is not a de Polignac number, because 61728357785 - 2²² = 61724163481 is a prime.

It is a super-3 number, since 3×61728357785³ (a number of 33 digits) contains 333 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6172835774 + ... + 6172835783.

It is an arithmetic number, because the mean of its divisors is an integer number (18518507337).

Almost surely, 2^61728357785 is an apocalyptic number.

It is an amenable number.

61728357785 is a deficient number, since it is larger than the sum of its proper divisors (12345671563).

61728357785 is a wasteful number, since it uses less digits than its factorization.

61728357785 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12345671562.

The product of its digits is 19756800, while the sum is 59.

The spelling of 61728357785 in words is "sixty-one billion, seven hundred twenty-eight million, three hundred fifty-seven thousand, seven hundred eighty-five".