20190781 has 16 divisors (see below), whose sum is σ = 23272704. Its totient is φ = 17351424.

The previous prime is 20190763. The next prime is 20190811. The reversal of 20190781 is 18709102.

It is not a de Polignac number, because 20190781 - 2¹⁷ = 20059709 is a prime.

It is a super-2 number, since 2×20190781² = 815335274779922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20190881) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 22320 + ... + 23206.

It is an arithmetic number, because the mean of its divisors is an integer number (1454544).

Almost surely, 2^20190781 is an apocalyptic number.

It is an amenable number.

20190781 is a deficient number, since it is larger than the sum of its proper divisors (3081923).

20190781 is a wasteful number, since it uses less digits than its factorization.

20190781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1020.

The product of its (nonzero) digits is 1008, while the sum is 28.

The square root of 20190781 is about 4493.4152935156. The cubic root of 20190781 is about 272.3021305759.

Adding to 20190781 its reverse (18709102), we get a palindrome (38899883).

The spelling of 20190781 in words is "twenty million, one hundred ninety thousand, seven hundred eighty-one".