20891598 has 64 divisors (see below), whose sum is σ = 52157952. Its totient is φ = 5431680.

The previous prime is 20891597. The next prime is 20891603. The reversal of 20891598 is 89519802.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20891597) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 45088 + ... + 45548.

It is an arithmetic number, because the mean of its divisors is an integer number (814968).

Almost surely, 2^20891598 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20891598, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26078976).

20891598 is an abundant number, since it is smaller than the sum of its proper divisors (31266354).

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

20891598 is a wasteful number, since it uses less digits than its factorization.

20891598 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 569.

The product of its (nonzero) digits is 51840, while the sum is 42.

The square root of 20891598 is about 4570.7327640106. The cubic root of 20891598 is about 275.4168795679.

It can be divided in two parts, 208 and 91598, that added together give a triangular number (91806 = T₄₂₈).

The spelling of 20891598 in words is "twenty million, eight hundred ninety-one thousand, five hundred ninety-eight".