21901751 has 2 divisors, whose sum is σ = 21901752. Its totient is φ = 21901750.

The previous prime is 21901739. The next prime is 21901753. The reversal of 21901751 is 15710912.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21901751 is a prime.

Together with 21901753, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21901751.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21901753) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10950875 + 10950876.

It is an arithmetic number, because the mean of its divisors is an integer number (10950876).

Almost surely, 2^21901751 is an apocalyptic number.

21901751 is a deficient number, since it is larger than the sum of its proper divisors (1).

21901751 is an equidigital number, since it uses as much as digits as its factorization.

21901751 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 630, while the sum is 26.

The square root of 21901751 is about 4679.9306618795. The cubic root of 21901751 is about 279.7861930719.

The spelling of 21901751 in words is "twenty-one million, nine hundred one thousand, seven hundred fifty-one".