20521706 has 8 divisors (see below), whose sum is σ = 31363524. Its totient is φ = 10067200.

The previous prime is 20521679. The next prime is 20521723. The reversal of 20521706 is 60712502.

It can be written as a sum of positive squares in 2 ways, for example, as 15721225 + 4800481 = 3965^2 + 2191^2 .

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

It is a super-2 number, since 2×20521706² = 842280834300872, which contains 22 as substring.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 96695 + ... + 96906.

Almost surely, 2^20521706 is an apocalyptic number.

20521706 is a deficient number, since it is larger than the sum of its proper divisors (10841818).

20521706 is a wasteful number, since it uses less digits than its factorization.

20521706 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 193656.

The product of its (nonzero) digits is 840, while the sum is 23.

The square root of 20521706 is about 4530.0889615989. The cubic root of 20521706 is about 273.7817449616.

The spelling of 20521706 in words is "twenty million, five hundred twenty-one thousand, seven hundred six".