16021556657 has 4 divisors (see below), whose sum is σ = 16022079216. Its totient is φ = 16021034100.

The previous prime is 16021556647. The next prime is 16021556689. The reversal of 16021556657 is 75665512061.

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 not a de Polignac number, because 16021556657 - 2¹⁶ = 16021491121 is a prime.

It is a super-2 number, since 2×16021556657² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16021556647) 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, 212219 + ... + 277632.

It is an arithmetic number, because the mean of its divisors is an integer number (4005519804).

Almost surely, 2^16021556657 is an apocalyptic number.

It is an amenable number.

16021556657 is a deficient number, since it is larger than the sum of its proper divisors (522559).

16021556657 is an equidigital number, since it uses as much as digits as its factorization.

16021556657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 522558.

The product of its (nonzero) digits is 378000, while the sum is 44.

The spelling of 16021556657 in words is "sixteen billion, twenty-one million, five hundred fifty-six thousand, six hundred fifty-seven".