21057355 has 8 divisors (see below), whose sum is σ = 27566064. Its totient is φ = 15314400.

The previous prime is 21057341. The next prime is 21057419. The reversal of 21057355 is 55375012.

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

It is not a de Polignac number, because 21057355 - 2¹⁵ = 21024587 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, 191376 + ... + 191485.

It is an arithmetic number, because the mean of its divisors is an integer number (3445758).

Almost surely, 2^21057355 is an apocalyptic number.

21057355 is a deficient number, since it is larger than the sum of its proper divisors (6508709).

21057355 is a wasteful number, since it uses less digits than its factorization.

21057355 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 382877.

The product of its (nonzero) digits is 5250, while the sum is 28.

The square root of 21057355 is about 4588.8293714193. The cubic root of 21057355 is about 276.1433608998.

It can be divided in two parts, 21057 and 355, that added together give a palindrome (21412).

The spelling of 21057355 in words is "twenty-one million, fifty-seven thousand, three hundred fifty-five".