20670651521 has 4 divisors (see below), whose sum is σ = 22260701652. Its totient is φ = 19080601392.

The previous prime is 20670651493. The next prime is 20670651569. The reversal of 20670651521 is 12515607602.

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 11845927921 + 8824723600 = 108839^2 + 93940^2 .

It is a cyclic number.

It is not a de Polignac number, because 20670651521 - 2³⁰ = 19596909697 is a prime.

It is a super-2 number, since 2×20670651521² (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 (20670651721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 795025046 + ... + 795025071.

It is an arithmetic number, because the mean of its divisors is an integer number (5565175413).

Almost surely, 2^20670651521 is an apocalyptic number.

It is an amenable number.

20670651521 is a deficient number, since it is larger than the sum of its proper divisors (1590050131).

20670651521 is a wasteful number, since it uses less digits than its factorization.

20670651521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1590050130.

The product of its (nonzero) digits is 25200, while the sum is 35.

The spelling of 20670651521 in words is "twenty billion, six hundred seventy million, six hundred fifty-one thousand, five hundred twenty-one".