21090477547 has 4 divisors (see below), whose sum is σ = 21090894120. Its totient is φ = 21090060976.

The previous prime is 21090477497. The next prime is 21090477571. The reversal of 21090477547 is 74577409012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21090477547 is a prime.

It is a super-2 number, since 2×21090477547² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21090477497 and 21090477506.

It is not an unprimeable number, because it can be changed into a prime (21090477047) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 119818 + ... + 237775.

It is an arithmetic number, because the mean of its divisors is an integer number (5272723530).

Almost surely, 2^21090477547 is an apocalyptic number.

21090477547 is a deficient number, since it is larger than the sum of its proper divisors (416573).

21090477547 is an equidigital number, since it uses as much as digits as its factorization.

21090477547 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 416572.

The product of its (nonzero) digits is 493920, while the sum is 46.

The spelling of 21090477547 in words is "twenty-one billion, ninety million, four hundred seventy-seven thousand, five hundred forty-seven".