21361949 has 4 divisors (see below), whose sum is σ = 24413664. Its totient is φ = 18310236.

The previous prime is 21361933. The next prime is 21361957. The reversal of 21361949 is 94916312.

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 21361949 - 2⁴ = 21361933 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 (21361919) 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, 1525847 + ... + 1525860.

It is an arithmetic number, because the mean of its divisors is an integer number (6103416).

Almost surely, 2^21361949 is an apocalyptic number.

It is an amenable number.

21361949 is a deficient number, since it is larger than the sum of its proper divisors (3051715).

21361949 is an equidigital number, since it uses as much as digits as its factorization.

21361949 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3051714.

The product of its digits is 11664, while the sum is 35.

The square root of 21361949 is about 4621.8988522035. The cubic root of 21361949 is about 277.4684605553.

The spelling of 21361949 in words is "twenty-one million, three hundred sixty-one thousand, nine hundred forty-nine".