21251998 has 8 divisors (see below), whose sum is σ = 32353992. Its totient is φ = 10467336.

The previous prime is 21251987. The next prime is 21252001. The reversal of 21251998 is 89915212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a plaindrome in base 16.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 79165 + ... + 79432.

It is an arithmetic number, because the mean of its divisors is an integer number (4044249).

Almost surely, 2^21251998 is an apocalyptic number.

21251998 is a deficient number, since it is larger than the sum of its proper divisors (11101994).

21251998 is a wasteful number, since it uses less digits than its factorization.

21251998 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 158666.

The product of its digits is 12960, while the sum is 37.

The square root of 21251998 is about 4609.9889370800. The cubic root of 21251998 is about 276.9915935360.

The spelling of 21251998 in words is "twenty-one million, two hundred fifty-one thousand, nine hundred ninety-eight".