102090781 has 32 divisors (see below), whose sum is σ = 121856000. Its totient is φ = 84680640.

The previous prime is 102090749. The next prime is 102090787. The reversal of 102090781 is 187090201.

It is a 3-Lehmer number, since φ(102090781) divides (102090781-1)³.

It is a cyclic number.

It is a Carmichael number.

It is not a de Polignac number, because 102090781 - 2⁵ = 102090749 is a prime.

It is a super-2 number, since 2×102090781² = 20845055130379922, which contains 22 as substring.

It is a deceptive number, since it divides R_102090780.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (102090787) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 512920 + ... + 513118.

It is an arithmetic number, because the mean of its divisors is an integer number (3808000).

It is a Poulet number, since it divides 2^102090780-1.

Almost surely, 2^102090781 is an apocalyptic number.

It is an amenable number.

102090781 is a deficient number, since it is larger than the sum of its proper divisors (19765219).

102090781 is a wasteful number, since it uses less digits than its factorization.

102090781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 329.

The product of its (nonzero) digits is 1008, while the sum is 28.

The square root of 102090781 is about 10103.9982680125. The cubic root of 102090781 is about 467.3714456791.

The spelling of 102090781 in words is "one hundred two million, ninety thousand, seven hundred eighty-one".