21154801 has 4 divisors (see below), whose sum is σ = 21164004. Its totient is φ = 21145600.

The previous prime is 21154799. The next prime is 21154813. The reversal of 21154801 is 10845112.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 14137600 + 7017201 = 3760^2 + 2649^2 .

It is a cyclic number.

It is not a de Polignac number, because 21154801 - 2¹ = 21154799 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21154831) 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 3 ways as a sum of consecutive naturals, for example, 2121 + ... + 6841.

It is an arithmetic number, because the mean of its divisors is an integer number (5291001).

Almost surely, 2^21154801 is an apocalyptic number.

It is an amenable number.

21154801 is a deficient number, since it is larger than the sum of its proper divisors (9203).

21154801 is an equidigital number, since it uses as much as digits as its factorization.

21154801 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9202.

The product of its (nonzero) digits is 320, while the sum is 22.

The square root of 21154801 is about 4599.4348565884. The cubic root of 21154801 is about 276.5686701529.

Adding to 21154801 its reverse (10845112), we get a palindrome (31999913).

The spelling of 21154801 in words is "twenty-one million, one hundred fifty-four thousand, eight hundred one".