21553499 has 8 divisors (see below), whose sum is σ = 24148848. Its totient is φ = 19064160.

The previous prime is 21553487. The next prime is 21553517. The reversal of 21553499 is 99435512.

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

It is a cyclic number.

It is not a de Polignac number, because 21553499 - 2⁸ = 21553243 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21553459) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26072 + ... + 26885.

It is an arithmetic number, because the mean of its divisors is an integer number (3018606).

Almost surely, 2^21553499 is an apocalyptic number.

21553499 is a deficient number, since it is larger than the sum of its proper divisors (2595349).

21553499 is a wasteful number, since it uses less digits than its factorization.

21553499 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53005.

The product of its digits is 48600, while the sum is 38.

The square root of 21553499 is about 4642.5746089858. The cubic root of 21553499 is about 278.2953359470.

The spelling of 21553499 in words is "twenty-one million, five hundred fifty-three thousand, four hundred ninety-nine".