21957473 has 2 divisors, whose sum is σ = 21957474. Its totient is φ = 21957472.

The previous prime is 21957431. The next prime is 21957491. The reversal of 21957473 is 37475912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20729809 + 1227664 = 4553^2 + 1108^2 .

It is a cyclic number.

It is not a de Polignac number, because 21957473 - 2⁶ = 21957409 is a prime.

It is not a weakly prime, because it can be changed into another prime (21957493) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10978736 + 10978737.

It is an arithmetic number, because the mean of its divisors is an integer number (10978737).

Almost surely, 2^21957473 is an apocalyptic number.

It is an amenable number.

21957473 is a deficient number, since it is larger than the sum of its proper divisors (1).

21957473 is an equidigital number, since it uses as much as digits as its factorization.

21957473 is an evil number, because the sum of its binary digits is even.

The product of its digits is 52920, while the sum is 38.

The square root of 21957473 is about 4685.8801734573. The cubic root of 21957473 is about 280.0232676243.

The spelling of 21957473 in words is "twenty-one million, nine hundred fifty-seven thousand, four hundred seventy-three".