19721487937537 has 8 divisors (see below), whose sum is σ = 20260848629952. Its totient is φ = 19182461324400.

The previous prime is 19721487937519. The next prime is 19721487937561. The reversal of 19721487937537 is 73573978412791.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 19721487937537 - 2³¹ = 19719340453889 is a prime.

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 19721487937537.

It is not an unprimeable number, because it can be changed into a prime (19721487937337) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 83400139 + ... + 83636272.

It is an arithmetic number, because the mean of its divisors is an integer number (2532606078744).

Almost surely, 2^{19721487937537} is an apocalyptic number.

It is an amenable number.

19721487937537 is a deficient number, since it is larger than the sum of its proper divisors (539360692415).

19721487937537 is a wasteful number, since it uses less digits than its factorization.

19721487937537 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 167039639.

The product of its digits is 560105280, while the sum is 73.

The spelling of 19721487937537 in words is "nineteen trillion, seven hundred twenty-one billion, four hundred eighty-seven million, nine hundred thirty-seven thousand, five hundred thirty-seven".