20521538 has 4 divisors (see below), whose sum is σ = 30782310. Its totient is φ = 10260768.

The previous prime is 20521519. The next prime is 20521561. The reversal of 20521538 is 83512502.

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., 20457529 + 64009 = 4523^2 + 253^2 .

It is a super-2 number, since 2×20521538² = 842267043770888, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5130383 + ... + 5130386.

Almost surely, 2^20521538 is an apocalyptic number.

20521538 is a deficient number, since it is larger than the sum of its proper divisors (10260772).

20521538 is a wasteful number, since it uses less digits than its factorization.

20521538 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10260771.

The product of its (nonzero) digits is 2400, while the sum is 26.

The square root of 20521538 is about 4530.0704188787. The cubic root of 20521538 is about 273.7809978590.

The spelling of 20521538 in words is "twenty million, five hundred twenty-one thousand, five hundred thirty-eight".