21913138 has 8 divisors (see below), whose sum is σ = 35398188. Its totient is φ = 10113744.

The previous prime is 21913123. The next prime is 21913141. The reversal of 21913138 is 83131912.

It can be written as a sum of positive squares in 2 ways, for example, as 21874329 + 38809 = 4677^2 + 197^2 .

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

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 421381 + ... + 421432.

Almost surely, 2^21913138 is an apocalyptic number.

21913138 is a deficient number, since it is larger than the sum of its proper divisors (13485050).

21913138 is a wasteful number, since it uses less digits than its factorization.

21913138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 842828.

The product of its digits is 1296, while the sum is 28.

The square root of 21913138 is about 4681.1470816457. The cubic root of 21913138 is about 279.8346728092.

It can be divided in two parts, 2191 and 3138, that added together give a square (5329 = 73²).

The spelling of 21913138 in words is "twenty-one million, nine hundred thirteen thousand, one hundred thirty-eight".