21253558 has 4 divisors (see below), whose sum is σ = 31880340. Its totient is φ = 10626778.

The previous prime is 21253543. The next prime is 21253591. The reversal of 21253558 is 85535212.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5313388 + ... + 5313391.

It is an arithmetic number, because the mean of its divisors is an integer number (7970085).

Almost surely, 2^21253558 is an apocalyptic number.

21253558 is a deficient number, since it is larger than the sum of its proper divisors (10626782).

21253558 is a wasteful number, since it uses less digits than its factorization.

21253558 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10626781.

The product of its digits is 12000, while the sum is 31.

The square root of 21253558 is about 4610.1581317781. The cubic root of 21253558 is about 276.9983708802.

The spelling of 21253558 in words is "twenty-one million, two hundred fifty-three thousand, five hundred fifty-eight".