21216801 has 8 divisors (see below), whose sum is σ = 28823040. Its totient is φ = 13877552.

The previous prime is 21216791. The next prime is 21216809. The reversal of 21216801 is 10861212.

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 21216801 - 2⁶ = 21216737 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21216809) 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, 66561 + ... + 66878.

It is an arithmetic number, because the mean of its divisors is an integer number (3602880).

Almost surely, 2^21216801 is an apocalyptic number.

It is an amenable number.

21216801 is a deficient number, since it is larger than the sum of its proper divisors (7606239).

21216801 is a wasteful number, since it uses less digits than its factorization.

21216801 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133495.

The product of its (nonzero) digits is 192, while the sum is 21.

The square root of 21216801 is about 4606.1698839708. The cubic root of 21216801 is about 276.8385936434.

The spelling of 21216801 in words is "twenty-one million, two hundred sixteen thousand, eight hundred one".