21420355 has 8 divisors (see below), whose sum is σ = 28041264. Its totient is φ = 15578400.

The previous prime is 21420331. The next prime is 21420397. The reversal of 21420355 is 55302412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21420355 - 2⁷ = 21420227 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 194676 + ... + 194785.

It is an arithmetic number, because the mean of its divisors is an integer number (3505158).

Almost surely, 2^21420355 is an apocalyptic number.

21420355 is a deficient number, since it is larger than the sum of its proper divisors (6620909).

21420355 is a wasteful number, since it uses less digits than its factorization.

21420355 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 389477.

The product of its (nonzero) digits is 1200, while the sum is 22.

The square root of 21420355 is about 4628.2129380572. The cubic root of 21420355 is about 277.7211072244.

Adding to 21420355 its reverse (55302412), we get a palindrome (76722767).

The spelling of 21420355 in words is "twenty-one million, four hundred twenty thousand, three hundred fifty-five".