21138254 has 8 divisors (see below), whose sum is σ = 31752840. Its totient is φ = 10553976.

The previous prime is 21138253. The next prime is 21138277. The reversal of 21138254 is 45283112.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21138251) 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 3 ways as a sum of consecutive naturals, for example, 5744 + ... + 8675.

It is an arithmetic number, because the mean of its divisors is an integer number (3969105).

Almost surely, 2^21138254 is an apocalyptic number.

21138254 is a deficient number, since it is larger than the sum of its proper divisors (10614586).

21138254 is a wasteful number, since it uses less digits than its factorization.

21138254 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15154.

The product of its digits is 1920, while the sum is 26.

The square root of 21138254 is about 4597.6356967468. The cubic root of 21138254 is about 276.4965419159.

The spelling of 21138254 in words is "twenty-one million, one hundred thirty-eight thousand, two hundred fifty-four".