102121561 has 4 divisors (see below), whose sum is σ = 107496400. Its totient is φ = 96746724.

The previous prime is 102121531. The next prime is 102121577. The reversal of 102121561 is 165121201.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 165121201 = 7 ⋅23588743.

It is a cyclic number.

It is not a de Polignac number, because 102121561 - 2⁹ = 102121049 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (19), and also a Moran number because the ratio is a prime number: 5374819 = 102121561 / (1 + 0 + 2 + 1 + 2 + 1 + 5 + 6 + 1).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (102121531) 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, 2687391 + ... + 2687428.

It is an arithmetic number, because the mean of its divisors is an integer number (26874100).

Almost surely, 2^102121561 is an apocalyptic number.

It is an amenable number.

102121561 is a deficient number, since it is larger than the sum of its proper divisors (5374839).

102121561 is an equidigital number, since it uses as much as digits as its factorization.

102121561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5374838.

The product of its (nonzero) digits is 120, while the sum is 19.

The square root of 102121561 is about 10105.5213126291. The cubic root of 102121561 is about 467.4184112244.

Adding to 102121561 its reverse (165121201), we get a palindrome (267242762).

The spelling of 102121561 in words is "one hundred two million, one hundred twenty-one thousand, five hundred sixty-one".