20258991 has 20 divisors (see below), whose sum is σ = 30723352. Its totient is φ = 13300848.

The previous prime is 20258983. The next prime is 20258993. The reversal of 20258991 is 19985202.

It is not a de Polignac number, because 20258991 - 2³ = 20258983 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20258993) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 3561 + ... + 7293.

Almost surely, 2^20258991 is an apocalyptic number.

20258991 is a deficient number, since it is larger than the sum of its proper divisors (10464361).

20258991 is an equidigital number, since it uses as much as digits as its factorization.

20258991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3812 (or 3803 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 36.

The square root of 20258991 is about 4500.9988891356. The cubic root of 20258991 is about 272.6084230331.

The spelling of 20258991 in words is "twenty million, two hundred fifty-eight thousand, nine hundred ninety-one".