21425858 has 4 divisors (see below), whose sum is σ = 32138790. Its totient is φ = 10712928.

The previous prime is 21425851. The next prime is 21425881. The reversal of 21425858 is 85852412.

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., 10843849 + 10582009 = 3293^2 + 3253^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21425851) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5356463 + ... + 5356466.

Almost surely, 2^21425858 is an apocalyptic number.

21425858 is a deficient number, since it is larger than the sum of its proper divisors (10712932).

21425858 is a wasteful number, since it uses less digits than its factorization.

21425858 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10712931.

The product of its digits is 25600, while the sum is 35.

The square root of 21425858 is about 4628.8074058012. The cubic root of 21425858 is about 277.7448878510.

It can be divided in two parts, 2142 and 5858, that added together give a cube (8000 = 20³).

The spelling of 21425858 in words is "twenty-one million, four hundred twenty-five thousand, eight hundred fifty-eight".