21204951 has 8 divisors (see below), whose sum is σ = 28304640. Its totient is φ = 14120952.

The previous prime is 21204949. The next prime is 21205021. The reversal of 21204951 is 15940212.

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

It is not a de Polignac number, because 21204951 - 2¹ = 21204949 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21204251) 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, 285 + ... + 6518.

It is an arithmetic number, because the mean of its divisors is an integer number (3538080).

Almost surely, 2^21204951 is an apocalyptic number.

21204951 is a deficient number, since it is larger than the sum of its proper divisors (7099689).

21204951 is a wasteful number, since it uses less digits than its factorization.

21204951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7845.

The product of its (nonzero) digits is 720, while the sum is 24.

The square root of 21204951 is about 4604.8833861456. The cubic root of 21204951 is about 276.7870441147.

It can be divided in two parts, 21204 and 951, that added together give a triangular number (22155 = T₂₁₀).

The spelling of 21204951 in words is "twenty-one million, two hundred four thousand, nine hundred fifty-one".