21171351477 has 4 divisors (see below), whose sum is σ = 28228468640. Its totient is φ = 14114234316.

The previous prime is 21171351413. The next prime is 21171351491. The reversal of 21171351477 is 77415317112.

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 not a de Polignac number, because 21171351477 - 2⁶ = 21171351413 is a prime.

It is a super-2 number, since 2×21171351477² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21171351577) 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, 3528558577 + ... + 3528558582.

It is an arithmetic number, because the mean of its divisors is an integer number (7057117160).

Almost surely, 2^21171351477 is an apocalyptic number.

It is an amenable number.

21171351477 is a deficient number, since it is larger than the sum of its proper divisors (7057117163).

21171351477 is an equidigital number, since it uses as much as digits as its factorization.

21171351477 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7057117162.

The product of its digits is 41160, while the sum is 39.

Adding to 21171351477 its reverse (77415317112), we get a palindrome (98586668589).

The spelling of 21171351477 in words is "twenty-one billion, one hundred seventy-one million, three hundred fifty-one thousand, four hundred seventy-seven".