21420330 has 32 divisors (see below), whose sum is σ = 51897024. Its totient is φ = 5657856.

The previous prime is 21420293. The next prime is 21420331. The reversal of 21420330 is 3302412.

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

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21420331) 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, 127 + ... + 6546.

It is an arithmetic number, because the mean of its divisors is an integer number (1621782).

Almost surely, 2^21420330 is an apocalyptic number.

21420330 is an abundant number, since it is smaller than the sum of its proper divisors (30476694).

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

21420330 is a wasteful number, since it uses less digits than its factorization.

21420330 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6790.

The product of its (nonzero) digits is 144, while the sum is 15.

The square root of 21420330 is about 4628.2102372299. The cubic root of 21420330 is about 277.7209991803.

Adding to 21420330 its reverse (3302412), we get a palindrome (24722742).

The spelling of 21420330 in words is "twenty-one million, four hundred twenty thousand, three hundred thirty".