20564731 has 4 divisors (see below), whose sum is σ = 22434264. Its totient is φ = 18695200.

The previous prime is 20564717. The next prime is 20564743. The reversal of 20564731 is 13746502.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20564731 - 2⁷ = 20564603 is a prime.

It is a super-2 number, since 2×20564731² = 845816322204722, 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 20564731.

It is not an unprimeable number, because it can be changed into a prime (20564431) 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, 934750 + ... + 934771.

It is an arithmetic number, because the mean of its divisors is an integer number (5608566).

Almost surely, 2^20564731 is an apocalyptic number.

20564731 is a deficient number, since it is larger than the sum of its proper divisors (1869533).

20564731 is a wasteful number, since it uses less digits than its factorization.

20564731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1869532.

The product of its (nonzero) digits is 5040, while the sum is 28.

The square root of 20564731 is about 4534.8352781551. The cubic root of 20564731 is about 273.9729447419.

The spelling of 20564731 in words is "twenty million, five hundred sixty-four thousand, seven hundred thirty-one".