20521163477 has 16 divisors (see below), whose sum is σ = 21703610880. Its totient is φ = 19363344000.

The previous prime is 20521163473. The next prime is 20521163497. The reversal of 20521163477 is 77436112502.

It is a cyclic number.

It is not a de Polignac number, because 20521163477 - 2² = 20521163473 is a prime.

It is a super-2 number, since 2×20521163477² (a number of 21 digits) contains 22 as substring.

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 20521163477.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20521163473) 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, 2359577 + ... + 2368257.

It is an arithmetic number, because the mean of its divisors is an integer number (1356475680).

Almost surely, 2^20521163477 is an apocalyptic number.

It is an amenable number.

20521163477 is a deficient number, since it is larger than the sum of its proper divisors (1182447403).

20521163477 is a wasteful number, since it uses less digits than its factorization.

20521163477 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10084.

The product of its (nonzero) digits is 70560, while the sum is 38.

Adding to 20521163477 its reverse (77436112502), we get a palindrome (97957275979).

The spelling of 20521163477 in words is "twenty billion, five hundred twenty-one million, one hundred sixty-three thousand, four hundred seventy-seven".