21498521 has 4 divisors (see below), whose sum is σ = 23452944. Its totient is φ = 19544100.

The previous prime is 21498511. The next prime is 21498539. The reversal of 21498521 is 12589412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21498521 - 2¹⁴ = 21482137 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21498511) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 977195 + ... + 977216.

It is an arithmetic number, because the mean of its divisors is an integer number (5863236).

Almost surely, 2^21498521 is an apocalyptic number.

It is an amenable number.

21498521 is a deficient number, since it is larger than the sum of its proper divisors (1954423).

21498521 is a wasteful number, since it uses less digits than its factorization.

21498521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1954422.

The product of its digits is 5760, while the sum is 32.

The square root of 21498521 is about 4636.6497603334. The cubic root of 21498521 is about 278.0585120873.

The spelling of 21498521 in words is "twenty-one million, four hundred ninety-eight thousand, five hundred twenty-one".