20998137 has 4 divisors (see below), whose sum is σ = 27997520. Its totient is φ = 13998756.

The previous prime is 20998093. The next prime is 20998139. The reversal of 20998137 is 73189902.

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.

It is not a de Polignac number, because 20998137 - 2¹⁰ = 20997113 is a prime.

It is a super-4 number, since 4×20998137⁴ (a number of 30 digits) contains 4444 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20998095 and 20998104.

It is not an unprimeable number, because it can be changed into a prime (20998139) 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, 3499687 + ... + 3499692.

It is an arithmetic number, because the mean of its divisors is an integer number (6999380).

Almost surely, 2^20998137 is an apocalyptic number.

It is an amenable number.

20998137 is a deficient number, since it is larger than the sum of its proper divisors (6999383).

20998137 is an equidigital number, since it uses as much as digits as its factorization.

20998137 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6999382.

The product of its (nonzero) digits is 27216, while the sum is 39.

The square root of 20998137 is about 4582.3724204826. The cubic root of 20998137 is about 275.8842588639.

It can be divided in two parts, 209 and 98137, that added together give a triangular number (98346 = T₄₄₃).

The spelling of 20998137 in words is "twenty million, nine hundred ninety-eight thousand, one hundred thirty-seven".