21428026 has 4 divisors (see below), whose sum is σ = 32142042. Its totient is φ = 10714012.

The previous prime is 21428021. The next prime is 21428051. The reversal of 21428026 is 62082412.

It is a happy number.

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., 19368801 + 2059225 = 4401^2 + 1435^2 .

It is not an unprimeable number, because it can be changed into a prime (21428021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5357005 + ... + 5357008.

Almost surely, 2^21428026 is an apocalyptic number.

21428026 is a deficient number, since it is larger than the sum of its proper divisors (10714016).

21428026 is a wasteful number, since it uses less digits than its factorization.

21428026 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10714015.

The product of its (nonzero) digits is 1536, while the sum is 25.

The square root of 21428026 is about 4629.0415854689. The cubic root of 21428026 is about 277.7542555134.

The spelling of 21428026 in words is "twenty-one million, four hundred twenty-eight thousand, twenty-six".