20021249 has 4 divisors (see below), whose sum is σ = 20031936. Its totient is φ = 20010564.

The previous prime is 20021233. The next prime is 20021251. The reversal of 20021249 is 94212002.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 20021249 - 2⁴ = 20021233 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20021249.

It is not an unprimeable number, because it can be changed into a prime (20021299) 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, 1709 + ... + 6554.

It is an arithmetic number, because the mean of its divisors is an integer number (5007984).

It is a Proth number, since it is equal to 611 ⋅ 2¹⁵ + 1 and 611 < 2¹⁵.

Almost surely, 2^20021249 is an apocalyptic number.

It is an amenable number.

20021249 is a deficient number, since it is larger than the sum of its proper divisors (10687).

20021249 is an equidigital number, since it uses as much as digits as its factorization.

20021249 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10686.

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 20021249 is about 4474.5110347389. The cubic root of 20021249 is about 271.5378587346.

The spelling of 20021249 in words is "twenty million, twenty-one thousand, two hundred forty-nine".