20405051 has 4 divisors (see below), whose sum is σ = 20709672. Its totient is φ = 20100432.

The previous prime is 20405041. The next prime is 20405057. The reversal of 20405051 is 15050402.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20405051 - 2⁶ = 20404987 is a prime.

It is a super-2 number, since 2×20405051² = 832732212625202, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20405057) 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, 152210 + ... + 152343.

It is an arithmetic number, because the mean of its divisors is an integer number (5177418).

Almost surely, 2^20405051 is an apocalyptic number.

20405051 is a deficient number, since it is larger than the sum of its proper divisors (304621).

20405051 is an equidigital number, since it uses as much as digits as its factorization.

20405051 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 304620.

The product of its (nonzero) digits is 200, while the sum is 17.

The square root of 20405051 is about 4517.1950367457. The cubic root of 20405051 is about 273.2619909318.

Adding to 20405051 its reverse (15050402), we get a palindrome (35455453).

The spelling of 20405051 in words is "twenty million, four hundred five thousand, fifty-one".