20890251 has 8 divisors (see below), whose sum is σ = 30948560. Its totient is φ = 13926816.

The previous prime is 20890241. The next prime is 20890277. The reversal of 20890251 is 15209802.

It is not a de Polignac number, because 20890251 - 2¹⁵ = 20857483 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 773713 = 20890251 / (2 + 0 + 8 + 9 + 0 + 2 + 5 + 1).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20890201) 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, 386830 + ... + 386883.

It is an arithmetic number, because the mean of its divisors is an integer number (3868570).

Almost surely, 2^20890251 is an apocalyptic number.

20890251 is a deficient number, since it is larger than the sum of its proper divisors (10058309).

20890251 is an equidigital number, since it uses as much as digits as its factorization.

20890251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 773722 (or 773716 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 27.

The square root of 20890251 is about 4570.5854110825. The cubic root of 20890251 is about 275.4109602105.

The spelling of 20890251 in words is "twenty million, eight hundred ninety thousand, two hundred fifty-one".