15825805421 has 2 divisors, whose sum is σ = 15825805422. Its totient is φ = 15825805420.

The previous prime is 15825805399. The next prime is 15825805433. The reversal of 15825805421 is 12450852851.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11740806025 + 4084999396 = 108355^2 + 63914^2 .

It is an emirp because it is prime and its reverse (12450852851) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-15825805421 is a prime.

It is a super-3 number, since 3×15825805421³ (a number of 32 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15825805481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7912902710 + 7912902711.

It is an arithmetic number, because the mean of its divisors is an integer number (7912902711).

Almost surely, 2^15825805421 is an apocalyptic number.

It is an amenable number.

15825805421 is a deficient number, since it is larger than the sum of its proper divisors (1).

15825805421 is an equidigital number, since it uses as much as digits as its factorization.

15825805421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 128000, while the sum is 41.

The spelling of 15825805421 in words is "fifteen billion, eight hundred twenty-five million, eight hundred five thousand, four hundred twenty-one".