21279258 has 96 divisors (see below), whose sum is σ = 61955712. Its totient is φ = 5097600.

The previous prime is 21279253. The next prime is 21279263. The reversal of 21279258 is 85297212.

It is an interprime number because it is at equal distance from previous prime (21279253) and next prime (21279263).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21279253) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 17428 + ... + 18608.

It is an arithmetic number, because the mean of its divisors is an integer number (645372).

Almost surely, 2^21279258 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21279258, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30977856).

21279258 is an abundant number, since it is smaller than the sum of its proper divisors (40676454).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21279258 is a wasteful number, since it uses less digits than its factorization.

21279258 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1220 (or 1217 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 21279258 is about 4612.9446127176. The cubic root of 21279258 is about 277.1099755765.

The spelling of 21279258 in words is "twenty-one million, two hundred seventy-nine thousand, two hundred fifty-eight".