20405721297 has 96 divisors (see below), whose sum is σ = 31242931200. Its totient is φ = 11827835136.

The previous prime is 20405721283. The next prime is 20405721311. The reversal of 20405721297 is 79212750402.

It is an interprime number because it is at equal distance from previous prime (20405721283) and next prime (20405721311).

It is not a de Polignac number, because 20405721297 - 2¹⁸ = 20405459153 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is not an unprimeable number, because it can be changed into a prime (20405721097) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 113998354 + ... + 113998532.

It is an arithmetic number, because the mean of its divisors is an integer number (325447200).

Almost surely, 2^20405721297 is an apocalyptic number.

It is an amenable number.

20405721297 is a deficient number, since it is larger than the sum of its proper divisors (10837209903).

20405721297 is a wasteful number, since it uses less digits than its factorization.

20405721297 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 407 (or 394 counting only the distinct ones).

The product of its (nonzero) digits is 70560, while the sum is 39.

The spelling of 20405721297 in words is "twenty billion, four hundred five million, seven hundred twenty-one thousand, two hundred ninety-seven".