23151781 has 2 divisors, whose sum is σ = 23151782. Its totient is φ = 23151780.

The previous prime is 23151763. The next prime is 23151797. The reversal of 23151781 is 18715132.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21538881 + 1612900 = 4641^2 + 1270^2 .

It is a cyclic number.

It is not a de Polignac number, because 23151781 - 2¹⁵ = 23119013 is a prime.

It is a super-2 number, since 2×23151781² = 1072009926943922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (23151181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 11575890 + 11575891.

It is an arithmetic number, because the mean of its divisors is an integer number (11575891).

Almost surely, 2^23151781 is an apocalyptic number.

It is an amenable number.

23151781 is a deficient number, since it is larger than the sum of its proper divisors (1).

23151781 is an equidigital number, since it uses as much as digits as its factorization.

23151781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1680, while the sum is 28.

The square root of 23151781 is about 4811.6297654745. The cubic root of 23151781 is about 285.0108993472.

It can be divided in two parts, 23151 and 781, that added together give a palindrome (23932).

The spelling of 23151781 in words is "twenty-three million, one hundred fifty-one thousand, seven hundred eighty-one".