21400138 has 4 divisors (see below), whose sum is σ = 32100210. Its totient is φ = 10700068.

The previous prime is 21400121. The next prime is 21400151. The reversal of 21400138 is 83100412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 12201049 + 9199089 = 3493^2 + 3033^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5350033 + ... + 5350036.

Almost surely, 2^21400138 is an apocalyptic number.

21400138 is a deficient number, since it is larger than the sum of its proper divisors (10700072).

21400138 is a wasteful number, since it uses less digits than its factorization.

21400138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10700071.

The product of its (nonzero) digits is 192, while the sum is 19.

The square root of 21400138 is about 4626.0283181148. The cubic root of 21400138 is about 277.6337066347.

The spelling of 21400138 in words is "twenty-one million, four hundred thousand, one hundred thirty-eight".