20409690 has 64 divisors (see below), whose sum is σ = 59284224. Its totient is φ = 4389888.

The previous prime is 20409689. The next prime is 20409691. The reversal of 20409690 is 9690402.

It is an interprime number because it is at equal distance from previous prime (20409689) and next prime (20409691).

It is a super-2 number, since 2×20409690² = 833110891792200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is not an unprimeable number, because it can be changed into a prime (20409691) 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, 712 + ... + 6428.

It is an arithmetic number, because the mean of its divisors is an integer number (926316).

Almost surely, 2^20409690 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20409690, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29642112).

20409690 is an abundant number, since it is smaller than the sum of its proper divisors (38874534).

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

20409690 is a wasteful number, since it uses less digits than its factorization.

20409690 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5751.

The product of its (nonzero) digits is 3888, while the sum is 30.

The square root of 20409690 is about 4517.7084899316. The cubic root of 20409690 is about 273.2826976729.

The spelling of 20409690 in words is "twenty million, four hundred nine thousand, six hundred ninety".