20502581 has 4 divisors (see below), whose sum is σ = 22366464. Its totient is φ = 18638700.

The previous prime is 20502571. The next prime is 20502589. The reversal of 20502581 is 18520502.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20502581 is a prime.

It is a super-2 number, since 2×20502581² = 840711655323122, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20502589) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 931925 + ... + 931946.

It is an arithmetic number, because the mean of its divisors is an integer number (5591616).

Almost surely, 2^20502581 is an apocalyptic number.

It is an amenable number.

20502581 is a deficient number, since it is larger than the sum of its proper divisors (1863883).

20502581 is a wasteful number, since it uses less digits than its factorization.

20502581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1863882.

The product of its (nonzero) digits is 800, while the sum is 23.

The square root of 20502581 is about 4527.9775838668. The cubic root of 20502581 is about 273.6966691353.

The spelling of 20502581 in words is "twenty million, five hundred two thousand, five hundred eighty-one".