21355499 has 4 divisors (see below), whose sum is σ = 23296920. Its totient is φ = 19414080.

The previous prime is 21355483. The next prime is 21355501. The reversal of 21355499 is 99455312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21355499 - 2⁴ = 21355483 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21355409) 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, 970694 + ... + 970715.

It is an arithmetic number, because the mean of its divisors is an integer number (5824230).

Almost surely, 2^21355499 is an apocalyptic number.

21355499 is a deficient number, since it is larger than the sum of its proper divisors (1941421).

21355499 is a wasteful number, since it uses less digits than its factorization.

21355499 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1941420.

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

The square root of 21355499 is about 4621.2010343633. The cubic root of 21355499 is about 277.4405315849.

The spelling of 21355499 in words is "twenty-one million, three hundred fifty-five thousand, four hundred ninety-nine".