21720298 has 8 divisors (see below), whose sum is σ = 33273792. Its totient is φ = 10629036.

The previous prime is 21720277. The next prime is 21720311. The reversal of 21720298 is 89202712.

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

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, 115440 + ... + 115627.

It is an arithmetic number, because the mean of its divisors is an integer number (4159224).

Almost surely, 2^21720298 is an apocalyptic number.

21720298 is a deficient number, since it is larger than the sum of its proper divisors (11553494).

21720298 is a wasteful number, since it uses less digits than its factorization.

21720298 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 231116.

The product of its (nonzero) digits is 4032, while the sum is 31.

The square root of 21720298 is about 4660.5040499929. The cubic root of 21720298 is about 279.0113859941.

The spelling of 21720298 in words is "twenty-one million, seven hundred twenty thousand, two hundred ninety-eight".