21309102 has 32 divisors (see below), whose sum is σ = 47648160. Its totient is φ = 7058880.

The previous prime is 21309061. The next prime is 21309103. The reversal of 21309102 is 20190312.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21309103) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8202 + ... + 10482.

It is an arithmetic number, because the mean of its divisors is an integer number (1489005).

Almost surely, 2^21309102 is an apocalyptic number.

21309102 is an abundant number, since it is smaller than the sum of its proper divisors (26339058).

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

21309102 is a wasteful number, since it uses less digits than its factorization.

21309102 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2465 (or 2459 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 18.

The square root of 21309102 is about 4616.1782894511. The cubic root of 21309102 is about 277.2394632821.

Adding to 21309102 its reverse (20190312), we get a palindrome (41499414).

The spelling of 21309102 in words is "twenty-one million, three hundred nine thousand, one hundred two".