21820086 has 12 divisors (see below), whose sum is σ = 47276892. Its totient is φ = 7273356.

The previous prime is 21820069. The next prime is 21820087. The reversal of 21820086 is 68002812.

It is a super-2 number, since 2×21820086² = 952232306094792, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21820087) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 606096 + ... + 606131.

It is an arithmetic number, because the mean of its divisors is an integer number (3939741).

Almost surely, 2^21820086 is an apocalyptic number.

21820086 is an abundant number, since it is smaller than the sum of its proper divisors (25456806).

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

21820086 is a wasteful number, since it uses less digits than its factorization.

21820086 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1212235 (or 1212232 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 27.

The square root of 21820086 is about 4671.1974910081. The cubic root of 21820086 is about 279.4380139528.

Adding to 21820086 its reverse (68002812), we get a palindrome (89822898).

The spelling of 21820086 in words is "twenty-one million, eight hundred twenty thousand, eighty-six".