21221801 has 8 divisors (see below), whose sum is σ = 22231104. Its totient is φ = 20219760.

The previous prime is 21221791. The next prime is 21221821. The reversal of 21221801 is 10812212.

It is a happy number.

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

It is a de Polignac number, because none of the positive numbers 2^k-21221801 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21221801.

It is not an unprimeable number, because it can be changed into a prime (21221821) 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, 4706 + ... + 8036.

It is an arithmetic number, because the mean of its divisors is an integer number (2778888).

Almost surely, 2^21221801 is an apocalyptic number.

It is an amenable number.

21221801 is a deficient number, since it is larger than the sum of its proper divisors (1009303).

21221801 is a wasteful number, since it uses less digits than its factorization.

21221801 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3631.

The product of its (nonzero) digits is 64, while the sum is 17.

The square root of 21221801 is about 4606.7126022794. The cubic root of 21221801 is about 276.8603387413.

It can be divided in two parts, 21221 and 801, that added together give a palindrome (22022).

The spelling of 21221801 in words is "twenty-one million, two hundred twenty-one thousand, eight hundred one".