21309486 has 16 divisors (see below), whose sum is σ = 46493568. Its totient is φ = 6457400.

The previous prime is 21309437. The next prime is 21309487. The reversal of 21309486 is 68490312.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21309487) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 161370 + ... + 161501.

It is an arithmetic number, because the mean of its divisors is an integer number (2905848).

Almost surely, 2^21309486 is an apocalyptic number.

21309486 is an abundant number, since it is smaller than the sum of its proper divisors (25184082).

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

21309486 is a wasteful number, since it uses less digits than its factorization.

21309486 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 322887.

The product of its (nonzero) digits is 10368, while the sum is 33.

The square root of 21309486 is about 4616.2198821113. The cubic root of 21309486 is about 277.2411286004.

Adding to 21309486 its reverse (68490312), we get a palindrome (89799798).

The spelling of 21309486 in words is "twenty-one million, three hundred nine thousand, four hundred eighty-six".