20642539 has 8 divisors (see below), whose sum is σ = 22070880. Its totient is φ = 19238016.

The previous prime is 20642527. The next prime is 20642561. The reversal of 20642539 is 93524602.

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

It is not a de Polignac number, because 20642539 - 2¹³ = 20634347 is a prime.

It is a super-2 number, since 2×20642539² = 852228832733042, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20642539.

It is not an unprimeable number, because it can be changed into a prime (20642509) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4144 + ... + 7645.

It is an arithmetic number, because the mean of its divisors is an integer number (2758860).

Almost surely, 2^20642539 is an apocalyptic number.

20642539 is a deficient number, since it is larger than the sum of its proper divisors (1428341).

20642539 is a wasteful number, since it uses less digits than its factorization.

20642539 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11909.

The product of its (nonzero) digits is 12960, while the sum is 31.

The square root of 20642539 is about 4543.4061011536. The cubic root of 20642539 is about 274.3180413726.

The spelling of 20642539 in words is "twenty million, six hundred forty-two thousand, five hundred thirty-nine".