20219551 has 4 divisors (see below), whose sum is σ = 22057704. Its totient is φ = 18381400.

The previous prime is 20219539. The next prime is 20219557. The reversal of 20219551 is 15591202.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20219551 - 2¹⁵ = 20186783 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 (20219557) 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 3 ways as a sum of consecutive naturals, for example, 919060 + ... + 919081.

It is an arithmetic number, because the mean of its divisors is an integer number (5514426).

Almost surely, 2^20219551 is an apocalyptic number.

20219551 is a deficient number, since it is larger than the sum of its proper divisors (1838153).

20219551 is a wasteful number, since it uses less digits than its factorization.

20219551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1838152.

The product of its (nonzero) digits is 900, while the sum is 25.

The square root of 20219551 is about 4496.6155050215. The cubic root of 20219551 is about 272.4314043316.

The spelling of 20219551 in words is "twenty million, two hundred nineteen thousand, five hundred fifty-one".