20405401021 has 8 divisors (see below), whose sum is σ = 20560579704. Its totient is φ = 20250312960.

The previous prime is 20405401013. The next prime is 20405401097. The reversal of 20405401021 is 12010450402.

It can be written as a sum of positive squares in 4 ways, for example, as 4622504121 + 15782896900 = 67989^2 + 125630^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20405401021 - 2³ = 20405401013 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20405401021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20405402021) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 469801 + ... + 511393.

It is an arithmetic number, because the mean of its divisors is an integer number (2570072463).

Almost surely, 2^20405401021 is an apocalyptic number.

It is an amenable number.

20405401021 is a deficient number, since it is larger than the sum of its proper divisors (155178683).

20405401021 is a wasteful number, since it uses less digits than its factorization.

20405401021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45311.

The product of its (nonzero) digits is 320, while the sum is 19.

Adding to 20405401021 its reverse (12010450402), we get a palindrome (32415851423).

The spelling of 20405401021 in words is "twenty billion, four hundred five million, four hundred one thousand, twenty-one".