20284991 has 4 divisors (see below), whose sum is σ = 20833272. Its totient is φ = 19736712.

The previous prime is 20284981. The next prime is 20285003. The reversal of 20284991 is 19948202.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19948202 = 2 ⋅9974101.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20284991 is a prime.

It is a super-2 number, since 2×20284991² = 822961719740162, 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 (20284981) 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, 274085 + ... + 274158.

It is an arithmetic number, because the mean of its divisors is an integer number (5208318).

Almost surely, 2^20284991 is an apocalyptic number.

20284991 is a deficient number, since it is larger than the sum of its proper divisors (548281).

20284991 is an equidigital number, since it uses as much as digits as its factorization.

20284991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 548280.

The product of its (nonzero) digits is 10368, while the sum is 35.

The square root of 20284991 is about 4503.8862108184. The cubic root of 20284991 is about 272.7249933176.

The spelling of 20284991 in words is "twenty million, two hundred eighty-four thousand, nine hundred ninety-one".