20421836 has 12 divisors (see below), whose sum is σ = 35770728. Its totient is φ = 10201632.

The previous prime is 20421803. The next prime is 20421859. The reversal of 20421836 is 63812402.

It is a super-2 number, since 2×20421836² = 834102771221792, which contains 22 as substring.

It is a plaindrome in base 16.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5720 + ... + 8576.

It is an arithmetic number, because the mean of its divisors is an integer number (2980894).

Almost surely, 2^20421836 is an apocalyptic number.

It is an amenable number.

20421836 is a deficient number, since it is larger than the sum of its proper divisors (15348892).

20421836 is a wasteful number, since it uses less digits than its factorization.

20421836 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4648 (or 4646 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 26.

The square root of 20421836 is about 4519.0525555696. The cubic root of 20421836 is about 273.3368979640.

It can be divided in two parts, 204 and 21836, that multiplied together give a palindrome (4454544).

The spelling of 20421836 in words is "twenty million, four hundred twenty-one thousand, eight hundred thirty-six".