21457037761 has 2 divisors, whose sum is σ = 21457037762. Its totient is φ = 21457037760.

The previous prime is 21457037677. The next prime is 21457037773. The reversal of 21457037761 is 16773075412.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11684529025 + 9772508736 = 108095^2 + 98856^2 .

It is a cyclic number.

It is not a de Polignac number, because 21457037761 - 2¹⁵ = 21457004993 is a prime.

It is not a weakly prime, because it can be changed into another prime (21457037461) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10728518880 + 10728518881.

It is an arithmetic number, because the mean of its divisors is an integer number (10728518881).

Almost surely, 2^21457037761 is an apocalyptic number.

It is an amenable number.

21457037761 is a deficient number, since it is larger than the sum of its proper divisors (1).

21457037761 is an equidigital number, since it uses as much as digits as its factorization.

21457037761 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 246960, while the sum is 43.

The spelling of 21457037761 in words is "twenty-one billion, four hundred fifty-seven million, thirty-seven thousand, seven hundred sixty-one".