15550981 has 4 divisors (see below), whose sum is σ = 15655500. Its totient is φ = 15446464.

The previous prime is 15550979. The next prime is 15550991. The reversal of 15550981 is 18905551.

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 6604900 + 8946081 = 2570^2 + 2991^2 .

It is a cyclic number.

It is not a de Polignac number, because 15550981 - 2¹ = 15550979 is a prime.

It is a super-2 number, since 2×15550981² = 483666020124722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15550961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 52036 + ... + 52333.

It is an arithmetic number, because the mean of its divisors is an integer number (3913875).

Almost surely, 2^15550981 is an apocalyptic number.

It is an amenable number.

15550981 is a deficient number, since it is larger than the sum of its proper divisors (104519).

15550981 is a wasteful number, since it uses less digits than its factorization.

15550981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104518.

The product of its (nonzero) digits is 9000, while the sum is 34.

The square root of 15550981 is about 3943.4732153268. The cubic root of 15550981 is about 249.6046069871.

The spelling of 15550981 in words is "fifteen million, five hundred fifty thousand, nine hundred eighty-one".