21253946 has 12 divisors (see below), whose sum is σ = 37086138. Its totient is φ = 9108792.

The previous prime is 21253943. The next prime is 21253957. The reversal of 21253946 is 64935212.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 13608721 + 7645225 = 3689^2 + 2765^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21253943) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 108341 + ... + 108536.

Almost surely, 2^21253946 is an apocalyptic number.

21253946 is a deficient number, since it is larger than the sum of its proper divisors (15832192).

21253946 is a wasteful number, since it uses less digits than its factorization.

21253946 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 216893 (or 216886 counting only the distinct ones).

The product of its digits is 12960, while the sum is 32.

The square root of 21253946 is about 4610.2002125721. The cubic root of 21253946 is about 277.0000564758. Note that the first 4 decimals are identical.

The spelling of 21253946 in words is "twenty-one million, two hundred fifty-three thousand, nine hundred forty-six".