21430057 has 4 divisors (see below), whose sum is σ = 23378256. Its totient is φ = 19481860.

The previous prime is 21430037. The next prime is 21430063. The reversal of 21430057 is 75003412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21430057 - 2¹¹ = 21428009 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21430007) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 974083 + ... + 974104.

It is an arithmetic number, because the mean of its divisors is an integer number (5844564).

Almost surely, 2^21430057 is an apocalyptic number.

It is an amenable number.

21430057 is a deficient number, since it is larger than the sum of its proper divisors (1948199).

21430057 is a wasteful number, since it uses less digits than its factorization.

21430057 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1948198.

The product of its (nonzero) digits is 840, while the sum is 22.

The square root of 21430057 is about 4629.2609561354. The cubic root of 21430057 is about 277.7630306423.

Adding to 21430057 its reverse (75003412), we get a palindrome (96433469).

The spelling of 21430057 in words is "twenty-one million, four hundred thirty thousand, fifty-seven".