20497781 has 8 divisors (see below), whose sum is σ = 21081600. Its totient is φ = 19920208.

The previous prime is 20497717. The next prime is 20497811. The reversal of 20497781 is 18779402.

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

It is a cyclic number.

It is not a de Polignac number, because 20497781 - 2⁶ = 20497717 is a prime.

It is a super-2 number, since 2×20497781² = 840318051847922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20497481) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5540 + ... + 8466.

It is an arithmetic number, because the mean of its divisors is an integer number (2635200).

Almost surely, 2^20497781 is an apocalyptic number.

It is an amenable number.

20497781 is a deficient number, since it is larger than the sum of its proper divisors (583819).

20497781 is a wasteful number, since it uses less digits than its factorization.

20497781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3123.

The product of its (nonzero) digits is 28224, while the sum is 38.

The square root of 20497781 is about 4527.4475148808. The cubic root of 20497781 is about 273.6753084662.

The spelling of 20497781 in words is "twenty million, four hundred ninety-seven thousand, seven hundred eighty-one".