21170477 has 4 divisors (see below), whose sum is σ = 21517596. Its totient is φ = 20823360.

The previous prime is 21170453. The next prime is 21170507. The reversal of 21170477 is 77407112.

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 249001 + 20921476 = 499^2 + 4574^2 .

It is a cyclic number.

It is not a de Polignac number, because 21170477 - 2⁸ = 21170221 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21170407) 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, 173468 + ... + 173589.

It is an arithmetic number, because the mean of its divisors is an integer number (5379399).

Almost surely, 2^21170477 is an apocalyptic number.

It is an amenable number.

21170477 is a deficient number, since it is larger than the sum of its proper divisors (347119).

21170477 is an equidigital number, since it uses as much as digits as its factorization.

21170477 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 347118.

The product of its (nonzero) digits is 2744, while the sum is 29.

The square root of 21170477 is about 4601.1386634180. The cubic root of 21170477 is about 276.6369670221.

Adding to 21170477 its reverse (77407112), we get a palindrome (98577589).

The spelling of 21170477 in words is "twenty-one million, one hundred seventy thousand, four hundred seventy-seven".