21258951 has 16 divisors (see below), whose sum is σ = 33186048. Its totient is φ = 11851200.

The previous prime is 21258917. The next prime is 21258973. The reversal of 21258951 is 15985212.

It is not a de Polignac number, because 21258951 - 2¹⁰ = 21257927 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21258151) 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 15 ways as a sum of consecutive naturals, for example, 11485 + ... + 13206.

It is an arithmetic number, because the mean of its divisors is an integer number (2074128).

Almost surely, 2^21258951 is an apocalyptic number.

21258951 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21258951 is a deficient number, since it is larger than the sum of its proper divisors (11927097).

21258951 is a wasteful number, since it uses less digits than its factorization.

21258951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24742.

The product of its digits is 7200, while the sum is 33.

The square root of 21258951 is about 4610.7429986934. The cubic root of 21258951 is about 277.0217979518.

The spelling of 21258951 in words is "twenty-one million, two hundred fifty-eight thousand, nine hundred fifty-one".