21351030 has 16 divisors (see below), whose sum is σ = 51242544. Its totient is φ = 5693600.

The previous prime is 21351017. The next prime is 21351053. The reversal of 21351030 is 3015312.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 355821 + ... + 355880.

It is an arithmetic number, because the mean of its divisors is an integer number (3202659).

Almost surely, 2^21351030 is an apocalyptic number.

21351030 is an abundant number, since it is smaller than the sum of its proper divisors (29891514).

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

21351030 is a wasteful number, since it uses less digits than its factorization.

21351030 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 711711.

The product of its (nonzero) digits is 90, while the sum is 15.

The square root of 21351030 is about 4620.7174767562. The cubic root of 21351030 is about 277.4211771908.

Adding to 21351030 its reverse (3015312), we get a palindrome (24366342).

The spelling of 21351030 in words is "twenty-one million, three hundred fifty-one thousand, thirty".