16815961 has 2 divisors, whose sum is σ = 16815962. Its totient is φ = 16815960.

The previous prime is 16815949. The next prime is 16815971. The reversal of 16815961 is 16951861.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12638025 + 4177936 = 3555^2 + 2044^2 .

It is an emirp because it is prime and its reverse (16951861) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16815961 - 2¹¹ = 16813913 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 16815961.

It is not a weakly prime, because it can be changed into another prime (16815901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8407980 + 8407981.

It is an arithmetic number, because the mean of its divisors is an integer number (8407981).

Almost surely, 2^16815961 is an apocalyptic number.

It is an amenable number.

16815961 is a deficient number, since it is larger than the sum of its proper divisors (1).

16815961 is an equidigital number, since it uses as much as digits as its factorization.

16815961 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12960, while the sum is 37.

The square root of 16815961 is about 4100.7268867848. The cubic root of 16815961 is about 256.1969157539.

It can be divided in two parts, 168 and 15961, that added together give a square (16129 = 127²).

The spelling of 16815961 in words is "sixteen million, eight hundred fifteen thousand, nine hundred sixty-one".