21280346 has 4 divisors (see below), whose sum is σ = 31920522. Its totient is φ = 10640172.

The previous prime is 21280327. The next prime is 21280349. The reversal of 21280346 is 64308212.

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

It can be written as a sum of positive squares in only one way, i.e., 20349121 + 931225 = 4511^2 + 965^2 .

It is not an unprimeable number, because it can be changed into a prime (21280349) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5320085 + ... + 5320088.

Almost surely, 2^21280346 is an apocalyptic number.

21280346 is a deficient number, since it is larger than the sum of its proper divisors (10640176).

21280346 is a wasteful number, since it uses less digits than its factorization.

21280346 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10640175.

The product of its (nonzero) digits is 2304, while the sum is 26.

The square root of 21280346 is about 4613.0625402221. The cubic root of 21280346 is about 277.1146983370.

Adding to 21280346 its reverse (64308212), we get a palindrome (85588558).

The spelling of 21280346 in words is "twenty-one million, two hundred eighty thousand, three hundred forty-six".