21428835 has 16 divisors (see below), whose sum is σ = 35084544. Its totient is φ = 11162592.

The previous prime is 21428831. The next prime is 21428861. The reversal of 21428835 is 53882412.

It is not a de Polignac number, because 21428835 - 2² = 21428831 is a prime.

It is a super-4 number, since 4×21428835⁴ (a number of 30 digits) contains 4444 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21428796 and 21428805.

It is not an unprimeable number, because it can be changed into a prime (21428831) 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, 15967 + ... + 17256.

It is an arithmetic number, because the mean of its divisors is an integer number (2192784).

Almost surely, 2^21428835 is an apocalyptic number.

21428835 is a deficient number, since it is larger than the sum of its proper divisors (13655709).

21428835 is a wasteful number, since it uses less digits than its factorization.

21428835 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33274.

The product of its digits is 15360, while the sum is 33.

The square root of 21428835 is about 4629.1289677433. The cubic root of 21428835 is about 277.7577509414.

The spelling of 21428835 in words is "twenty-one million, four hundred twenty-eight thousand, eight hundred thirty-five".