20402372261 has 2 divisors, whose sum is σ = 20402372262. Its totient is φ = 20402372260.

The previous prime is 20402372257. The next prime is 20402372281. The reversal of 20402372261 is 16227320402.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14766867361 + 5635504900 = 121519^2 + 75070^2 .

It is a cyclic number.

It is not a de Polignac number, because 20402372261 - 2² = 20402372257 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20402372251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10201186130 + 10201186131.

It is an arithmetic number, because the mean of its divisors is an integer number (10201186131).

Almost surely, 2^20402372261 is an apocalyptic number.

It is an amenable number.

20402372261 is a deficient number, since it is larger than the sum of its proper divisors (1).

20402372261 is an equidigital number, since it uses as much as digits as its factorization.

20402372261 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8064, while the sum is 29.

Adding to 20402372261 its reverse (16227320402), we get a palindrome (36629692663).

The spelling of 20402372261 in words is "twenty billion, four hundred two million, three hundred seventy-two thousand, two hundred sixty-one".