23129781 has 16 divisors (see below), whose sum is σ = 32272128. Its totient is φ = 14720000.

The previous prime is 23129779. The next prime is 23129803. The reversal of 23129781 is 18792132.

23129781 = 731² + 732² + ... + 771².

It is a cyclic number.

It is not a de Polignac number, because 23129781 - 2¹ = 23129779 is a prime.

It is a super-2 number, since 2×23129781² = 1069973538215922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (23129081) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3781 + ... + 7781.

It is an arithmetic number, because the mean of its divisors is an integer number (2017008).

Almost surely, 2^23129781 is an apocalyptic number.

It is an amenable number.

23129781 is a deficient number, since it is larger than the sum of its proper divisors (9142347).

23129781 is a wasteful number, since it uses less digits than its factorization.

23129781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4092.

The product of its digits is 6048, while the sum is 33.

The square root of 23129781 is about 4809.3430944361. The cubic root of 23129781 is about 284.9205934519.

The spelling of 23129781 in words is "twenty-three million, one hundred twenty-nine thousand, seven hundred eighty-one".