21701538 has 24 divisors (see below), whose sum is σ = 47286876. Its totient is φ = 7192800.

The previous prime is 21701531. The next prime is 21701551. The reversal of 21701538 is 83510712.

It can be written as a sum of positive squares in 2 ways, for example, as 21594609 + 106929 = 4647^2 + 327^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21701531) 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 11 ways as a sum of consecutive naturals, for example, 73 + ... + 6588.

Almost surely, 2^21701538 is an apocalyptic number.

21701538 is an abundant number, since it is smaller than the sum of its proper divisors (25585338).

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

21701538 is a wasteful number, since it uses less digits than its factorization.

21701538 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6850 (or 6847 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 27.

The square root of 21701538 is about 4658.4909573809. The cubic root of 21701538 is about 278.9310347134.

The spelling of 21701538 in words is "twenty-one million, seven hundred one thousand, five hundred thirty-eight".