15212280781 has 4 divisors (see below), whose sum is σ = 15351843100. Its totient is φ = 15072718464.

The previous prime is 15212280779. The next prime is 15212280793. The reversal of 15212280781 is 18708221251.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6486852681 + 8725428100 = 80541^2 + 93410^2 .

It is a cyclic number.

It is not a de Polignac number, because 15212280781 - 2¹ = 15212280779 is a prime.

It is a super-2 number, since 2×15212280781² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 15212280781.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15212280701) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 69780996 + ... + 69781213.

It is an arithmetic number, because the mean of its divisors is an integer number (3837960775).

Almost surely, 2^15212280781 is an apocalyptic number.

It is an amenable number.

15212280781 is a deficient number, since it is larger than the sum of its proper divisors (139562319).

15212280781 is a wasteful number, since it uses less digits than its factorization.

15212280781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 139562318.

The product of its (nonzero) digits is 17920, while the sum is 37.

It can be divided in two parts, 152122 and 80781, that added together give a triangular number (232903 = T₆₈₂).

The spelling of 15212280781 in words is "fifteen billion, two hundred twelve million, two hundred eighty thousand, seven hundred eighty-one".