20402421 has 16 divisors (see below), whose sum is σ = 29500800. Its totient is φ = 12467520.

The previous prime is 20402419. The next prime is 20402441. The reversal of 20402421 is 12420402.

It is not a de Polignac number, because 20402421 - 2¹ = 20402419 is a prime.

It is a super-2 number, since 2×20402421² = 832517565322482, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 20402421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20402411) 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, 4056 + ... + 7566.

It is an arithmetic number, because the mean of its divisors is an integer number (1843800).

Almost surely, 2^20402421 is an apocalyptic number.

It is an amenable number.

20402421 is a deficient number, since it is larger than the sum of its proper divisors (9098379).

20402421 is a wasteful number, since it uses less digits than its factorization.

20402421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3676.

The product of its (nonzero) digits is 128, while the sum is 15.

The square root of 20402421 is about 4516.9039175081. The cubic root of 20402421 is about 273.2502502127.

Adding to 20402421 its reverse (12420402), we get a palindrome (32822823).

The spelling of 20402421 in words is "twenty million, four hundred two thousand, four hundred twenty-one".