21020427 has 12 divisors (see below), whose sum is σ = 30499560. Its totient is φ = 13950528.

The previous prime is 21020411. The next prime is 21020429. The reversal of 21020427 is 72402012.

It is not a de Polignac number, because 21020427 - 2⁴ = 21020411 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020429) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3102 + ... + 7187.

It is an arithmetic number, because the mean of its divisors is an integer number (2541630).

Almost surely, 2^21020427 is an apocalyptic number.

21020427 is a deficient number, since it is larger than the sum of its proper divisors (9479133).

21020427 is a wasteful number, since it uses less digits than its factorization.

21020427 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10522 (or 10519 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 18.

The square root of 21020427 is about 4584.8039216525. The cubic root of 21020427 is about 275.9818434811.

Adding to 21020427 its reverse (72402012), we get a palindrome (93422439).

The spelling of 21020427 in words is "twenty-one million, twenty thousand, four hundred twenty-seven".