21417961 has 4 divisors (see below), whose sum is σ = 21427524. Its totient is φ = 21408400.

The previous prime is 21417953. The next prime is 21417971. The reversal of 21417961 is 16971412.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 8886361 + 12531600 = 2981^2 + 3540^2 .

It is a cyclic number.

It is not a de Polignac number, because 21417961 - 2³ = 21417953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21417971) 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, 591 + ... + 6571.

It is an arithmetic number, because the mean of its divisors is an integer number (5356881).

Almost surely, 2^21417961 is an apocalyptic number.

It is an amenable number.

21417961 is a deficient number, since it is larger than the sum of its proper divisors (9563).

21417961 is an equidigital number, since it uses as much as digits as its factorization.

21417961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9562.

The product of its digits is 3024, while the sum is 31.

The square root of 21417961 is about 4627.9542996879. The cubic root of 21417961 is about 277.7107605378.

The spelling of 21417961 in words is "twenty-one million, four hundred seventeen thousand, nine hundred sixty-one".