20402408569 has 3 divisors (see below), whose sum is σ = 20402551407. Its totient is φ = 20402265732.

The previous prime is 20402408567. The next prime is 20402408627. The reversal of 20402408569 is 96580420402.

The square root of 20402408569 is 142837.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 5423586025 + 14978822544 = 73645^2 + 122388^2 .

It is not a de Polignac number, because 20402408569 - 2¹ = 20402408567 is a prime.

It is a super-2 number, since 2×20402408569² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20402408567) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 71419 + ... + 214255.

It is an arithmetic number, because the mean of its divisors is an integer number (6800850469).

Almost surely, 2^20402408569 is an apocalyptic number.

20402408569 is the 142837-th square number.

20402408569 is the 71419-th centered octagonal number.

It is an amenable number.

20402408569 is a deficient number, since it is larger than the sum of its proper divisors (142838).

20402408569 is an frugal number, since it uses more digits than its factorization.

20402408569 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 285674 (or 142837 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 40.

The spelling of 20402408569 in words is "twenty billion, four hundred two million, four hundred eight thousand, five hundred sixty-nine".