21295423777 has 2 divisors, whose sum is σ = 21295423778. Its totient is φ = 21295423776.

The previous prime is 21295423733. The next prime is 21295423783. The reversal of 21295423777 is 77732459212.

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., 14090639616 + 7204784161 = 118704^2 + 84881^2 .

It is a cyclic number.

It is not a de Polignac number, because 21295423777 - 2³¹ = 19147940129 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21295423777.

It is not a weakly prime, because it can be changed into another prime (21295423717) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10647711888 + 10647711889.

It is an arithmetic number, because the mean of its divisors is an integer number (10647711889).

Almost surely, 2^21295423777 is an apocalyptic number.

It is an amenable number.

21295423777 is a deficient number, since it is larger than the sum of its proper divisors (1).

21295423777 is an equidigital number, since it uses as much as digits as its factorization.

21295423777 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1481760, while the sum is 49.

The spelling of 21295423777 in words is "twenty-one billion, two hundred ninety-five million, four hundred twenty-three thousand, seven hundred seventy-seven".