21154051 has 4 divisors (see below), whose sum is σ = 21372232. Its totient is φ = 20935872.

The previous prime is 21154039. The next prime is 21154097. The reversal of 21154051 is 15045112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21154051 - 2⁵ = 21154019 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21152051) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 108945 + ... + 109138.

It is an arithmetic number, because the mean of its divisors is an integer number (5343058).

Almost surely, 2^21154051 is an apocalyptic number.

21154051 is a deficient number, since it is larger than the sum of its proper divisors (218181).

21154051 is an equidigital number, since it uses as much as digits as its factorization.

21154051 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 218180.

The product of its (nonzero) digits is 200, while the sum is 19.

The square root of 21154051 is about 4599.3533241098. The cubic root of 21154051 is about 276.5654017230.

Adding to 21154051 its reverse (15045112), we get a palindrome (36199163).

The spelling of 21154051 in words is "twenty-one million, one hundred fifty-four thousand, fifty-one".