102561921 has 24 divisors (see below), whose sum is σ = 184701504. Its totient is φ = 53278560.

The previous prime is 102561911. The next prime is 102561947. The reversal of 102561921 is 129165201.

102561921 is a `hidden beast` number, since 1 + 0 + 25 + 619 + 21 = 666.

It is not a de Polignac number, because 102561921 - 2⁵ = 102561889 is a prime.

It is not an unprimeable number, because it can be changed into a prime (102561911) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 73306 + ... + 74691.

It is an arithmetic number, because the mean of its divisors is an integer number (7695896).

Almost surely, 2^102561921 is an apocalyptic number.

102561921 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

102561921 is a deficient number, since it is larger than the sum of its proper divisors (82139583).

102561921 is a wasteful number, since it uses less digits than its factorization.

102561921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 148021 (or 148018 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 27.

The square root of 102561921 is about 10127.2859641663. The cubic root of 102561921 is about 468.0893019374.

The spelling of 102561921 in words is "one hundred two million, five hundred sixty-one thousand, nine hundred twenty-one".