21304906 has 12 divisors (see below), whose sum is σ = 37175058. Its totient is φ = 9130632.

The previous prime is 21304897. The next prime is 21304919. The reversal of 21304906 is 60940312.

It can be written as a sum of positive squares in only one way, i.e., 20385225 + 919681 = 4515^2 + 959^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 108601 + ... + 108796.

Almost surely, 2^21304906 is an apocalyptic number.

21304906 is a deficient number, since it is larger than the sum of its proper divisors (15870152).

21304906 is a wasteful number, since it uses less digits than its factorization.

21304906 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 217413 (or 217406 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 25.

The square root of 21304906 is about 4615.7237785639. The cubic root of 21304906 is about 277.2212649061.

The spelling of 21304906 in words is "twenty-one million, three hundred four thousand, nine hundred six".