20971998 has 48 divisors (see below), whose sum is σ = 47848320. Its totient is φ = 6625872.

The previous prime is 20971997. The next prime is 20972023. The reversal of 20971998 is 89917902.

It is a super-2 number, since 2×20971998² = 879649400224008, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20971997) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 73965 + ... + 74247.

It is an arithmetic number, because the mean of its divisors is an integer number (996840).

Almost surely, 2^20971998 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20971998, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23924160).

20971998 is an abundant number, since it is smaller than the sum of its proper divisors (26876322).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20971998 is a wasteful number, since it uses less digits than its factorization.

20971998 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 493 (or 490 counting only the distinct ones).

The product of its (nonzero) digits is 81648, while the sum is 45.

The square root of 20971998 is about 4579.5194070994. The cubic root of 20971998 is about 275.7697354819.

It can be divided in two parts, 2097 and 1998, that added together give a triangular number (4095 = T₉₀).

The spelling of 20971998 in words is "twenty million, nine hundred seventy-one thousand, nine hundred ninety-eight".