21367949 has 4 divisors (see below), whose sum is σ = 21415164. Its totient is φ = 21320736.

The previous prime is 21367933. The next prime is 21367979. The reversal of 21367949 is 94976312.

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 19096900 + 2271049 = 4370^2 + 1507^2 .

It is a cyclic number.

It is not a de Polignac number, because 21367949 - 2⁴ = 21367933 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 (21367909) 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, 22922 + ... + 23835.

It is an arithmetic number, because the mean of its divisors is an integer number (5353791).

Almost surely, 2^21367949 is an apocalyptic number.

It is an amenable number.

21367949 is a deficient number, since it is larger than the sum of its proper divisors (47215).

21367949 is an equidigital number, since it uses as much as digits as its factorization.

21367949 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47214.

The product of its digits is 81648, while the sum is 41.

The square root of 21367949 is about 4622.5478905037. The cubic root of 21367949 is about 277.4944359461.

The spelling of 21367949 in words is "twenty-one million, three hundred sixty-seven thousand, nine hundred forty-nine".