21421254 has 16 divisors (see below), whose sum is σ = 42900480. Its totient is φ = 7130760.

The previous prime is 21421249. The next prime is 21421259. The reversal of 21421254 is 45212412.

It is an interprime number because it is at equal distance from previous prime (21421249) and next prime (21421259).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21421254.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21421259) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3507 + ... + 7425.

It is an arithmetic number, because the mean of its divisors is an integer number (2681280).

Almost surely, 2^21421254 is an apocalyptic number.

21421254 is an abundant number, since it is smaller than the sum of its proper divisors (21479226).

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

21421254 is a wasteful number, since it uses less digits than its factorization.

21421254 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4835.

The product of its digits is 640, while the sum is 21.

The square root of 21421254 is about 4628.3100587579. The cubic root of 21421254 is about 277.7249924352.

Adding to 21421254 its reverse (45212412), we get a palindrome (66633666).

The spelling of 21421254 in words is "twenty-one million, four hundred twenty-one thousand, two hundred fifty-four".