21131738 has 4 divisors (see below), whose sum is σ = 31697610. Its totient is φ = 10565868.

The previous prime is 21131723. The next prime is 21131771. The reversal of 21131738 is 83713112.

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., 12411529 + 8720209 = 3523^2 + 2953^2 .

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5282933 + ... + 5282936.

Almost surely, 2^21131738 is an apocalyptic number.

21131738 is a deficient number, since it is larger than the sum of its proper divisors (10565872).

21131738 is a wasteful number, since it uses less digits than its factorization.

21131738 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10565871.

The product of its digits is 1008, while the sum is 26.

The square root of 21131738 is about 4596.9270170408. The cubic root of 21131738 is about 276.4681283957.

The spelling of 21131738 in words is "twenty-one million, one hundred thirty-one thousand, seven hundred thirty-eight".