21172898 has 4 divisors (see below), whose sum is σ = 31759350. Its totient is φ = 10586448.

The previous prime is 21172891. The next prime is 21172913. The reversal of 21172898 is 89827112.

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., 13010449 + 8162449 = 3607^2 + 2857^2 .

It is not an unprimeable number, because it can be changed into a prime (21172891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5293223 + ... + 5293226.

Almost surely, 2^21172898 is an apocalyptic number.

21172898 is a deficient number, since it is larger than the sum of its proper divisors (10586452).

21172898 is a wasteful number, since it uses less digits than its factorization.

21172898 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10586451.

The product of its digits is 16128, while the sum is 38.

The square root of 21172898 is about 4601.4017429475. The cubic root of 21172898 is about 276.6475117785.

The spelling of 21172898 in words is "twenty-one million, one hundred seventy-two thousand, eight hundred ninety-eight".