21154021 has 8 divisors (see below), whose sum is σ = 25009920. Its totient is φ = 17506608.

The previous prime is 21154019. The next prime is 21154027. The reversal of 21154021 is 12045112.

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

It is not a de Polignac number, because 21154021 - 2¹ = 21154019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21153986 and 21154004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21154027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 51901 + ... + 52306.

It is an arithmetic number, because the mean of its divisors is an integer number (3126240).

Almost surely, 2^21154021 is an apocalyptic number.

It is an amenable number.

21154021 is a deficient number, since it is larger than the sum of its proper divisors (3855899).

21154021 is a wasteful number, since it uses less digits than its factorization.

21154021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104243.

The product of its (nonzero) digits is 80, while the sum is 16.

The square root of 21154021 is about 4599.3500627806. The cubic root of 21154021 is about 276.5652709842.

Adding to 21154021 its reverse (12045112), we get a palindrome (33199133).

The spelling of 21154021 in words is "twenty-one million, one hundred fifty-four thousand, twenty-one".