16720561551 has 16 divisors (see below), whose sum is σ = 23289880320. Its totient is φ = 10650245760.

The previous prime is 16720561549. The next prime is 16720561573. The reversal of 16720561551 is 15516502761.

It is a happy number.

It is not a de Polignac number, because 16720561551 - 2¹ = 16720561549 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16720561511) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 76741 + ... + 198318.

It is an arithmetic number, because the mean of its divisors is an integer number (1455617520).

Almost surely, 2^16720561551 is an apocalyptic number.

16720561551 is a deficient number, since it is larger than the sum of its proper divisors (6569318769).

16720561551 is a wasteful number, since it uses less digits than its factorization.

16720561551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 275966.

The product of its (nonzero) digits is 63000, while the sum is 39.

The spelling of 16720561551 in words is "sixteen billion, seven hundred twenty million, five hundred sixty-one thousand, five hundred fifty-one".