21023178751 has 2 divisors, whose sum is σ = 21023178752. Its totient is φ = 21023178750.

The previous prime is 21023178733. The next prime is 21023178763. The reversal of 21023178751 is 15787132012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21023178751 - 2²³ = 21014790143 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21023178751.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21023178721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10511589375 + 10511589376.

It is an arithmetic number, because the mean of its divisors is an integer number (10511589376).

Almost surely, 2^21023178751 is an apocalyptic number.

21023178751 is a deficient number, since it is larger than the sum of its proper divisors (1).

21023178751 is an equidigital number, since it uses as much as digits as its factorization.

21023178751 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 23520, while the sum is 37.

The spelling of 21023178751 in words is "twenty-one billion, twenty-three million, one hundred seventy-eight thousand, seven hundred fifty-one".