16781209357 has 4 divisors (see below), whose sum is σ = 18306773856. Its totient is φ = 15255644860.

The previous prime is 16781209307. The next prime is 16781209391. The reversal of 16781209357 is 75390218761.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16781209357 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 16781209357.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16781209307) 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, 762782233 + ... + 762782254.

It is an arithmetic number, because the mean of its divisors is an integer number (4576693464).

Almost surely, 2^16781209357 is an apocalyptic number.

It is an amenable number.

16781209357 is a deficient number, since it is larger than the sum of its proper divisors (1525564499).

16781209357 is a wasteful number, since it uses less digits than its factorization.

16781209357 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1525564498.

The product of its (nonzero) digits is 635040, while the sum is 49.

The spelling of 16781209357 in words is "sixteen billion, seven hundred eighty-one million, two hundred nine thousand, three hundred fifty-seven".