21621201 has 12 divisors (see below), whose sum is σ = 33535152. Its totient is φ = 12354888.

The previous prime is 21621181. The next prime is 21621233. The reversal of 21621201 is 10212612.

It is not a de Polignac number, because 21621201 - 2⁶ = 21621137 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21621001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 73395 + ... + 73688.

It is an arithmetic number, because the mean of its divisors is an integer number (2794596).

Almost surely, 2^21621201 is an apocalyptic number.

21621201 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21621201 is a deficient number, since it is larger than the sum of its proper divisors (11913951).

21621201 is a wasteful number, since it uses less digits than its factorization.

21621201 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 147100 (or 147093 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 15.

The square root of 21621201 is about 4649.8603204828. The cubic root of 21621201 is about 278.5864171892.

Adding to 21621201 its reverse (10212612), we get a palindrome (31833813).

The spelling of 21621201 in words is "twenty-one million, six hundred twenty-one thousand, two hundred one".