25785861421 has 2 divisors, whose sum is σ = 25785861422. Its totient is φ = 25785861420.

The previous prime is 25785861371. The next prime is 25785861481. The reversal of 25785861421 is 12416858752.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16662937225 + 9122924196 = 129085^2 + 95514^2 .

It is a cyclic number.

It is not a de Polignac number, because 25785861421 - 2¹³ = 25785853229 is a prime.

It is a super-2 number, since 2×25785861421² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25785861481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12892930710 + 12892930711.

It is an arithmetic number, because the mean of its divisors is an integer number (12892930711).

Almost surely, 2^25785861421 is an apocalyptic number.

It is an amenable number.

25785861421 is a deficient number, since it is larger than the sum of its proper divisors (1).

25785861421 is an equidigital number, since it uses as much as digits as its factorization.

25785861421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1075200, while the sum is 49.

The spelling of 25785861421 in words is "twenty-five billion, seven hundred eighty-five million, eight hundred sixty-one thousand, four hundred twenty-one".